Price cut for vermin (3)
I believe the answer is:
rat
'vermin' is the definition.
(I've seen this in other clues)
'price cut' is the wordplay.
'price' becomes 'rate' (I've seen this in other clues).
'cut' means to remove the last letter.
'rate' with its final letter removed is 'RAT'.
'for' is the link.
(Other definitions for rat that I've seen before include "shopper" , "Rodent; informer (colloq.)" , "Desert - rodent" , "Betrayer" , "one who betrayed" .)