Artist on the subject of film genre (6)
I believe the answer is:
renoir
'artist' is the definition.
(French artist Pierre-Auguste Renoir)
'the subject of film genre' is the wordplay.
'the subject of' becomes 're' ('re' means regarding or about).
'film genre' becomes 'noir' (film noir).
're'+'noir'='RENOIR'
'on' is the link.
(Other definitions for renoir that I've seen before include "Pierre-Auguste -, French Impressionist painter" , "'No, I err, he was a painter (6)'" , "Pierre Auguste ---, painter; Jean ---, film-director" , "French artist" , "Fr. impressionist ('La Loge')" .)