Carp (7)
'carp' is the definition.
(I know that carp can be written as cavil)
This is all the clue.
(Other definitions for cavil that I've seen before include "Make petty objections" , "Carp" , "Nitpick" , "Quibble" , "Object unnecessarily" .)
'carp' is the definition.
(both can mean to find fault with something)
This is the entire clue.
(Other definitions for nitpick that I've seen before include "Find fault fussily" , "Have little complaint" , "Be fussy and pedantic" , "Raise petty objections" , "Be fussily pedantic" .)