Severely injure (4)
I believe the answer is:
maim
'severely injure' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for maim that I've seen before include "Hurt badly" , "Wound or injure, disable" , "seriously hurt!" , "Injure (a person), causing permanent disability" , "Wound and cripple" .)