Charge cut for informer (3)
I believe the answer is:
rat
'informer' is the definition.
(synonyms)
'charge cut' is the wordplay.
'charge' becomes 'rate' (rate is a kind of charge).
'cut' means to remove the last letter.
'rate' with its final letter taken away is 'RAT'.
'for' acts as a link.
(Other definitions for rat that I've seen before include "Grass" , "Plague-carrying rodent" , "Betrayer" , "Despicable person" , "person doing shopping" .)