Nag about wife getting bite (4)
I believe the answer is:
gnaw
'bite' is the definition.
(gnawing is a kind of biting)
'nag about wife getting' is the wordplay.
'about' is an anagram indicator.
'wife' becomes 'w'.
'getting' is a charade indicator (letters next to each other).
'nag' anagrammed gives 'gna'.
'gna'+'w'='GNAW'
(Other definitions for gnaw that I've seen before include "Bite and wear away" , "Chew steadily at" , "Bite persistently, grind" , "Wear away with the teeth" , "Nibble like a rodent" .)