Aluminum wrap (4)
I believe the answer is:
foil
'aluminum wrap' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for foil that I've seen before include "Prevent from succeeding" , "Parry" , "Thin metal sheet; frustrate" , "Scotch" , "Prevent the success of; fencing sword" .)