Singer Young or Diamond
I believe the answer is:
neil
This clue is a double definition.
'singer young' is the first definition.
(I've seen this in another clue)
'diamond' is the second definition.
(I've seen this in another clue)
(Other definitions for neil that I've seen before include "- Simon, US dramatist (Barefoot in the Park)" , "- Armstrong, first man to walk on the moon" , "- Armstrong, first man to set foot on the Moon" , "Boy's name" , "Boy" .)