Gabe Kaplan -- Giving Back SOME of His Celebrity Poker Winnings

"Welcome Back Kotter" star Gabe Kaplan is forking over almost half his winnings from those Hollywood poker games involving a ponzi crook, Tobey Maguire, and several other big name celebs.

Kaplan was one of the defendants in the lawsuits filed earlier this year ... by a bankruptcy trustee trying to recover cash convicted ponzi schemer Bradley Ruderman lost in the high-stakes poker tournaments.

According to court documents filed last week -- Kaplan won a total of $62,000 from Ruderman ... but as part of a settlement he's agreeing to return $27,900 to the trustee.

Tobey is fighting the lawsuit against him and has refused to hand over any of his winnings.

Kaplan's proposed settlement was submitted to the judge on Friday, but has not been approved yet.