Bedevil (7)
I believe the answer is:
torment
'bedevil' is the definition.
(I know that bedevil can be written as torment)
This is all the clue.
(Other definitions for torment that I've seen before include "Punish" , "Hound" , "Extreme mental or physical distress" , "Cause mental distress" , "Severe pain" .)