Bobby Clampett, 22, shot a six-under-par 64 yesterday in Columbus, Ga., to win the Southern Open golf tournament by two strokes over Hale Irwin for his first victory in slightly more than two years on the PGA tour.

Clampett, clad in gray knickers and white shoes, won $45,000 for his four-round 266 total.

Irwin shot a tournament record 61 on the par-70 Green Island Country Club course for a 72-hole total of 268.

George Burns, the third-round leader, shot 68 and finished third at 269 . . .

Gene Littler fired his fourth consecutive sub-par round, a two-under-par 70, and finished with an eight-under par 280 to win the $150,000 World Seniors Invitational golf tournament in Charlotte, N.C. . . .

In London, Gordon Brand Jr. became the first professional to win two tournaments in his rookie year on the European tour with his victory in the Bob Hope British Golf Classic. Brand finished with a 69 for a 16-under four-round total of 272, three shots ahead of Mark James . . .

In Kent, Wash., Patty Sheehan parred the final hole for a one-stroke victory in the Ladies Professional Golf Association's $175,000 Safeco Classic.

Sheehan and JoAnne Carner were tied at 12 under par going to the last hole at the Meridian Valley Country Club. Sheehan won $26,250 in the 72-hole tournament.