...according to one-time artiste (9)
I believe the answer is:
performer
'artiste' is the definition.
(I've seen this before)
'according to one-time' is the wordplay.
'according to' becomes 'per' (I've seen this in another clue).
'one-time' becomes 'former' (I've seen this before).
'per'+'former'='PERFORMER'
(Other definitions for performer that I've seen before include "artist" , "Such as a musician or actor" , "Fred Astaire, say" , "clown possibly" , "Eg 9 [ACTRESS]" .)