Second-rate fool and singer? (4)
I believe the answer is:
bass
'singer?' is the definition.
(bass is a kind of singer)
'second-rate fool' is the wordplay.
'second rate' becomes 'b'.
'fool' becomes 'ass' (ass is a kind of fool).
'b'+'ass'='BASS'
'and' is the link.
(Other definitions for bass that I've seen before include "Fish (which sings?)" , "Fish; deep voice" , "Deep-toned" , "Low-pitched; a fish" , "bottom of sound?" .)