Kawhi Leonard returned from a three-game absence caused by a knee injury to score 17 points on seven-of-20 shooting.
The Clippers win takes them to nine and one defeat at home, taking them to the fourth best record overall in the Western Conference.
In overtime, George hit a 3-pointer after he missed his first attempt and Beverley got the offensive rebound, then George fed Beverley for a 3 of his own.
Yet the presence of the full squad as constructed, marked a cause for satisfaction, punctuated by a fierce fourth-quarter comeback at Staples Center.
Kemba finally looked like himself when he drained a long three with 8:12 left, giving the Cs their largest lead to that point at 81-73.
Leonard was seen after the morning shootaround getting shots up.
Marcus Smart can't say he told you so.
The back-and-forth nature of the contest saw Williams hit a go-ahead three-pointer with 31 seconds remaining in regulation.
With the crowd on its feet shouting "Defense!" Defence!' Williams stole the ball at the other end and got fouled, making both free throws for a 97-94 lead.
Tatum missed a tying three-point attempt with 2.6 seconds left, and Leonard blocked Walker's last-gasp three-point attempt just before time expired. But the Clippers responded with a 10-0 run led by Williams and Beverley, taking a 3-point lead. Lou Williams scored 27 points, while Beverley was left alone on several shots, drilling four 3-pointers, two of them coming in overtime. Tatum connected on back-to-back 3s later in the period.
Celtics: They dominated in the paint, 52-32.
George put up 25 points and eight assists, while Leonard finished with a 17-point haul that included a dazzling dunk over the towering Daniel Theis.
Clippers: Their bench outscored the Celtics' reserves 43-29.
As for other stats, both teams tied in total rebounds (53) and assists (26), while the Clippers had one more steal, indicating the tightness of this game.
Celtics: At the Denver Nuggets on Friday to end a five-game swing out West. Patrick Beverley corralled a career-best 16 rebounds to go along with 14 points and seven assists, and JaMychal Green added 10 points as Los Angeles won their third straight game.