Bandmate of Lennon, McCartney and Harrison (5)
I believe the answer is:
starr
(Other definitions for starr that I've seen before include "Ringo --, drummer" , "Beatle Ringo" , "Freddie . . . . . Ate My Hamster" , "English rock star and drummer, b. 1940" , "Ringo - (The Beatles)" .)