Interior design credo made up (5)
I believe the answer is:
decor
'interior design' is the definition.
(I've seen this in another clue)
'credo made up' is the wordplay.
'made up' indicates an anagram.
'credo' with letters rearranged gives 'DECOR'.
(Other definitions for decor that I've seen before include "furnishings required" , "Scheme of interior furnishings" , "Interior colour scheme and furnishing" , "Style of furnishing etc used in room" , "Room colour scheme, furnishings, etc" .)