Entertainer who’s first rate all round, potentially (7)
I believe the answer is:
Here is my best explanation:
'entertainer' is the definition.
(artiste is a kind of entertainer)
'first rate all round potentially' is the wordplay.
I cannot quite see how this works, but
'first' could be 'ist' and 'ist' is present in the answer.
an anagram of 'rate' is 'arte' which is present in the remaining letters.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
'who's' is the link.
(Other definitions for artiste that I've seen before include "Theatre performer", "An entertainer", "Attires (anag.)", "A public performer", "Performers", "Tears it (anag.)", "Attires for professional entertainer", "Professional entertainer", "A sitter for creative person" and "nightclub entertainer?".)