"The Dance" painter (7)
I believe the answer is:
'the dance painter' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for matisse that I've seen before include "French painter, d. 1954" , "French painter, Henri, d.1954" , "20th century French painter" , "Henri --, French artist" , "Leading fauvist painter, d. 1954" .)