Blight (4)
I believe the answer is:
bane
'blight' is the definition.
(bane is a kind of blight)
This is all the clue.
(Other definitions for bane that I've seen before include "Something causing misery or distress" , "scourge" , "Curse" , "Affliction, cause of distress" , "Cause of great distress in a bean" .)