Interior design (5)
I believe the answer is:
decor
'interior design' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for decor that I've seen before include "stage background" , "Credo (anag.)" , "furnishings required" , "Furnishings and colours of a room" , "Style of furnishing etc used in room" .)