U2 lead singer (4)
I believe the answer is:
bono
'u2 lead singer' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for bono that I've seen before include "U2's star vocalist" , "U2 frontman" , "Famous singer in famous band" , "Singer in a leading band" , "U2's main singer and lyricist" .)