Corrosive (7)
I believe the answer is:
caustic
'corrosive' is the definition.
(I know that corrosive can be written as caustic)
This is the entire clue.
(Other definitions for caustic that I've seen before include "Corrosive - cutting" , "Biting (wit); burning" , "Acrimonious - sarcastic" , "Acrid" , "Scathing" .)