The Boston Red Sox clung to first place in the hectic American League East pennant race yesterday by downing the Kansas City Royals in Fenway Park while the Detroit Tigers were losing to the New York Yankees in a 12-inning contest in Detroit.

Doug Griffin lashed a run-scoring single and Reggie Smith banged out two doubles and scored two runs to lead the Boston Red Sox to a 3-1 victory over the Kansas City Royals yesterday afternoon.

In Detroit good things were happening as far as Boston fans were concerned. The Yankees, riding three home runs, knocked off the second-place Tigers, 3-2, in 12 innings. Roy White's solo circuit in the top of the twelfth was the decisive blow, as the New Yorkers overcame some stout pitching by Mickey Lolich to push the Tigers one step closer to elimination, while keeping their own slim pennant hopes alive. Ex-Soxer Sparky Lyle got the win.

John Curtis, rookie southpaw who started for Boston, gave up seven hits while running his season record to 11-7. Loser Dick Drago (11-17) surrendered only five for the Royals in a losing effort.

Griffin's two-out single in the second inning brought home Rico Petrocelli, who had singled and moved to second on Carlton Fisk's single to give the Sox a quick 1-0 lead.

In the fourth inning. Smith laced a double to lead off and then stole third. He then raced home when Drago uncorked a wold pitch to up the margin to 2-0.

The Royals broke into the scoring column in the sixth, when Cookie Rojas grounded into a force play after the Royals had loaded the bases off Curtis. But the rally was short-lived as the Sox defense tightened to cut off the Kansas City threat