Works by French author favour British publisher (5,3,4)
I believe the answer is:
mills and boon
'british publisher' is the definition.
(publisher of romance novels)
'works by french author favour' is the wordplay.
'works by' becomes 'mill' (mill is a kind of works. I am not sure about the 'by' bit.).
'french author' becomes 'sand' (novelist George Sand).
'favour' becomes 'boon' (I've seen this before).
'mill'+'sand'+'boon'='MILLS AND BOON'
Can you help me to learn more?
(Another definition for mills and boon that I've seen is " Publisher of romantic novels".)