Complain querulously (4)
I believe the answer is:
carp
'complain querulously' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for carp that I've seen before include "Complain continually" , "Continuously find fault" , "Keep complaining" , "Complain like goldfish" , "Pond fish" .)