Singing voice; fish (4)
I believe the answer is:
bass
This clue is a double definition.
'singing voice' is the first definition.
(I know that bass is a type of singing voice)
'fish' is the second definition.
(bass is a kind of fish)
(Other definitions for bass that I've seen before include "Fish; male singing voice" , "Type of fish" , "Fish; vocalist" , "Fish, guitar" , "Lowest adult male singing voice" .)