Uncovered a painting (4)
I believe the answer is:
nude
This clue is a double definition.
'uncovered' is the first definition.
(I've seen this in another clue)
'a painting' is the second definition.
(nude painting is a kind of painting)
(Other definitions for nude that I've seen before include "Naked, bare" , "Wearing one's birthday suit" , "rejecting coverage?" , "Naked person" , "Undressed" .)