Possibly crude painting (3)
I believe the answer is:
oil
This clue is a double definition.
'possibly crude' is the first definition.
(crude oil is a type of oil)
'painting' is the second definition.
(oil painting is a kind of painting)
(Other definitions for oil that I've seen before include "Lubricate; fuel" , "Cooking agent" , "Valuable viscous liquid" , "Type of fuel" , "Liquid fuel" .)