Harold —, comedian who played the title role in 1947 film The Sin of Harold Diddlebock (5)
I believe the answer is:
lloyd
(Other definitions for lloyd that I've seen before include "Frank -- Wright, US architect" , "David -- George, PM 1916-22" , "Harold --; -- George" , "David - George, British PM nineteen sixteen to nineteen twenty two" , "Andrew -- Webber, composer" .)