A standard love affair for a courtesan (8)
I believe the answer is:
paramour
'for a courtesan' is the definition.
('paramour' can be a synonym of 'courtesan')
'a standard love affair' is the wordplay.
'a standard' becomes 'par' (standard of play in golf).
'love affair' becomes 'amour' (I've seen this in another clue).
'par'+'amour'='PARAMOUR'
(Other definitions for paramour that I've seen before include "Lover, usually illicit" , "wife's toy boy, for example" , "Lover, especially of a married person" , "Mistress, lover" , "A married person's secret lover" .)