Prima donna very keen to return (4)
I believe the answer is:
diva
'prima donna' is the definition.
('diva' can be a synonym of 'prima donna')
'very keen to return' is the wordplay.
'very keen' becomes 'avid' (I've seen this before).
'to return' shows that the letters should be reversed in order.
'avid' written backwards gives 'DIVA'.
(Other definitions for diva that I've seen before include "Operatic soprano" , "For example Sutherland" , "Great performer" , "High-maintenace woman" , "Grand female singer" .)