The most common and most likely answer to this crossword clue is the 7 letter word MATISSE
I've seen this crossword clue in Financial Times
M
A
T
I
S
S
E
More clues leading to the result MATISSE
- Painter’s assistant is second to be accepted
- Painter putting vacuous art in skip at bottom of drive
- Painter harboured by diplomat is secure
- Artist makes a mess with it
- Artist‘s mother to pose for painters around the London area
- Artist taking degree at various sites
- Samiest, re-hashed figure in collage
- Trapped in laundromat is sensitive artist
- Painter is special to be embraced by comrade
- Confrère of Whistler‘s mother upset English model cuddling son
Buddy explains!

The straight part
We know that "Artist" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case artist = matisse.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.