Double clutch doesn’t even begin to describe it.

When Hauns Brereton nailed an improbable, hanging line-drive 3-pointer to earn overtime for Hawaii against No. 14 Xavier last Friday, it wasn’t just for him, or even for the UH fan base in general.

Brereton needed to settle up with his little brother, Landon, who watched in the wee hours of the morning at the family household back in Memphis, Tenn.

“I gotta perform because I know my little brother’s watching. He gets excitement from seeing me do well,” Brereton said.

The 6-foot-6 junior swingman will look to build on some recent success — and continue to live up to his double-clutch nicknames, “Iceman” and “Ketchup” — when UH (7-5) takes on South Carolina State (4-8) on Thursday and No. 19 UNLV (13-2) on New Year’s Eve.

The Rainbow Warriors need Brereton to play well for several reasons — not the least of which is to space the floor as a secondary shooter. Brereton needs no extra motivation, however.

Landon, 13, was diagnosed with medulloblastoma at age 5, a form of brain and spinal cancer. The years since have been a series of trials — ones that Landon has passed at every stage at the St. Jude’s Children’s Hospital in Memphis. Brereton sees it as a duty to help the youngest of his four siblings get through everything from chemotherapy to myriad doctor’s appointments.

“I’m always calling him. He actually makes deals with me,” Hauns said. “He knows I was struggling these past games and he started making bets with me. He said if I don’t do well, ‘You’re going to owe me five bucks.’ “

Hauns estimates he owes Landon $20, if not more.

It’s true that most of the first 10 games of Brereton’s UH career were a struggle. Before last week, he had one double-digit scoring game, and his role was unclear with a diminished ability to hit an open 3-point shot. He shot over 40 percent from deep as a third-team junior college All-American at Western Nebraska Community College last year, but currently stands at 26.1 percent (6-for-23) for UH.

A stat that is completely forgiven after what happened in the Hawaiian Airlines Diamond Head Classic consolation semifinal.

UH needed a spirited rally from 15 points down to send the game into overtime against the Musketeers for its first win over a ranked team in six years. But even after a valiant push, UH still needed a 3 in the final seconds.

Brereton was feeling it that night — he finished 6-for-7 for 13 points — but still hadn’t hit a 3 since six games prior, when he scored a season-high 14 in a loss at Pepperdine.

UH coach Gib Arnold put Brereton in to complement shooting guard Zane Johnson. And it was Brereton, not Johnson, who took a handoff from point guard Miah Ostrowski, dribbled above the top of the arc and let one fly with 2 seconds left after hanging in midair to let a Xavier defender pass him by.

Somehow, it went in. And the Brereton household — like the Stan Sheriff Center — went nuts.

“It was awesome, especially how he made the double-clutch 3 … to send it to overtime,” Landon said. “I was like, ‘Yes, yes!’ I was just really happy for Hauns. It’s hard to explain, but I was just really happy and excited. Then on SportsCenter the next day, me and my family watched it over and over. I loved it.”

UH went on to win that game on a basket by Joston Thomas in overtime. A clearly confident Brereton followed it up with a 10-point game in a win over Clemson for the DHC consolation championship.

But everything kept going back to the double-clutch 3.

“I watched the replay of it, I have no idea how he made that,” Johnson said. “I tried to do it in warmups the other day when we were messing around, (and) I couldn’t make it. I shot it about five times. I dunno, it was a great shot. He says he’s practiced it and made it before. He said that’s his No. 1 shot in H-O-R-S-E.”

Brereton may have been bluffing.

“Yeah, I’ve never shot a double clutch since like fifth grade,” he conceded. “That was the thing to do when you were in elementary school.”

His sudden success likely comes from a few factors.

Landon’s health has been mostly promising, and Brereton, who is a quarter Samoan, says he feels more comfortable here since tapping into some of his Polynesian roots with local relatives. Also, Brereton has bought in to his role as a rebounder, shooter and gritty defender.

Arnold’s faith in Brereton is high after the junior proved himself in practices recently, particularly on defense.

“I kept telling my family and friends, ‘You wait. There’s going to be a breakout day. He’s just too good of a player to go this long without one,’ ” Arnold said. “This week we saw a lot more of what we expect out of Hauns.”

He once helped his club team catch up from a 12-point deficit with 2 minutes left, and was sometimes known as “Hines,” so hence, “Ketchup.”

He had a similar 3 as his shot against Xavier to send a Bartlett High rivalry game to overtime — where he won it with a free throw — for the origin of “Iceman.”

If anyone needs to look for justification for double-clutch nicknames, just queue up the instant-classic Xavier game. There’s a decent chance Landon Brereton is watching it on a loop back in Tennessee.