Decorative pillowcase (4)
I believe the answer is:
sham
'decorative pillowcase' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sham that I've seen before include "Mock" , "Mash, being false" , "Counterfeit, fake" , "Feign" , "Counterfeit or insincere" .)