A stunning actress who asked Bill Cosby for career advice accused the comedy legend of hanky-panky after the two dined alone at his swank East Side townhouse, law-enforcement sources said yesterday. Lachele Covington, 20, who has appeared on Cosby’s CBS TV show, filed a police report saying the beloved comedian put her hand under his T-shirt and guided it south toward his sweatpants, the sources said. But Covington said she pulled her hand away — and that was the end of that. She told Cosby she was leaving and he said, “That’s fine.”