Decorative plaster (6)
I believe the answer is:
stucco
'decorative plaster' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for stucco that I've seen before include "Plaster used to coat walls" , "Type of plastering for outside walls" , "Kind of plaster moulded into decorations" , "Plaster used for moulding decorations on walls or ceilings" , "Fine plaster used in cornices, mouldings" .)