Plague insect (6)
I believe the answer is:
locust
'plague insect' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for locust that I've seen before include "beast resulting in destruction" , "Destructive migratory insect" , "Grasshopper of warm regions" , "Clouts (anag)" , "Destructive winged insect" .)