Fold covering over device (4)
I believe the answer is:
ploy
'device' is the definition.
(I've seen this before)
'fold covering over' is the wordplay.
'fold' becomes 'ply' (I've seen this before).
'covering' is an insertion indicator.
'over' becomes 'o' (cricket abbreviation).
'ply' going around 'o' is 'PLOY'.
(Other definitions for ploy that I've seen before include "Trick" , "Game manoeuvre" , "Cunning tactic" , "Cunning manoeuvre to gain advantage" , "Tactical scheme" .)