Destructive rodent (3)
I believe the answer is:
rat
'destructive rodent' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for rat that I've seen before include "Scumbag" , "Rodent; informer (colloq.)" , "one escaping doomed vessel?" , "person doing shopping" , "Tell-tale" .)