Rest for artist after rest left (5)
I believe the answer is:
easel
'rest for artist' is the definition.
(where an artist's canvas rests)
'after rest left' is the wordplay.
'after' means one lot of letters go next to another.
'rest' becomes 'ease' (synonyms).
'left' becomes 'L' (common abbreviation).
'ease'+'l' is 'EASEL'.
(Other definitions for easel that I've seen before include "supporter of board, perhaps" , "Artistic support" , "Artist's canvas suppot" , "Tripod supporting a canvas" , "The rest of artists" .)