Plywood layer (6)
I believe the answer is:
veneer
'plywood layer' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for veneer that I've seen before include "Thin layer glued to the top" , "Misleading external appearance" , "Superficial polish" , "Thin wood facing" , "Disguise" .)