The Fab Four (7)
I believe the answer is:
beatles
'the fab four' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for beatles that I've seen before include "British pop band of the 60s" , "The Fab Four composer-singers" , "Group of British" , "Able set? (anag)" , "Be least among fabulous four" .)