Carp and egg served with cream (7)
I believe the answer is:
nitpick
'carp' is the definition.
(both can mean to find fault with something)
'egg served with cream' is the wordplay.
'egg' becomes 'nit' (nit is a kind of egg).
'served with' means one lot of letters go next to another.
'cream' becomes 'pick' ('pick' can be a synonym of 'cream').
'nit'+'pick'='NITPICK'
'and' is the link.
(Other definitions for nitpick that I've seen before include "Make petty criticism" , "Criticise pettily" , "Choose carefully" , "Find fault fussily" , "Have little complaint" .)