Protection from a terrible enemy (3)
I believe the answer is:
lee
'protection' is the definition.
(I've seen this in another clue)
'from a terrible enemy' is the wordplay.
'from' indicates a hidden word.
'LEE' can be found hidden inside 'terrible enemy'.
(Other definitions for lee that I've seen before include "Robert E. - - , US hero" , "The sheltered side of something" , "Revolutionary general" , "Commander of the Confederate States Army in the American Civil War" , "actor" .)