There's something fishy about this singer (4)
I believe the answer is:
bass
'this singer' is the definition.
(bass is a kind of singer)
'there's something fishy about' is the wordplay.
I cannot really understand how this works, but
'about' could be 'a' (abbreviation in Chambers) and 'a' is located in the answer.
The remaining letters 'bss' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for bass that I've seen before include "Fish; male singing voice" , "Variety of sea and freshwater perch" , "Low singer" , "Large percussion instrument" , "Type of fish" .)