Singer; fish (4)
I believe the answer is:
bass
I believe this is a double definition.
'singer' is the first definition.
(I know that bass is a type of singer)
'fish' is the second definition.
(bass is a kind of fish)
(Other definitions for bass that I've seen before include "Freshwater fish and lowest voice" , "Fish; male singing voice" , "Low singing voice" , "Fish; deep voice" , "Type of fish" .)