Artist's paint board (7)
I believe the answer is:
palette
'artist's paint board' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for palette that I've seen before include "Range of colours - what artist mixes them on" , "Artist's paint mixing board" , "Artists mix on this" , "Artist's range of colours" , "Board on which painter mixes colours" .)