Plaster of Paris (5)
I believe the answer is:
gesso
'plaster of paris' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for gesso that I've seen before include "smeared on for starters by artists" , "Artist's plaster" , "Could get you plastered" , "Plaster of Paris" , "Type of plaster" .)