A fine, fine romance (6)
I believe the answer is:
affair
'romance' is the definition.
(I've seen this before)
'a fine fine' is the wordplay.
'a fine' becomes 'af' (I've seen this in other clues).
'fine' becomes 'fair' (I've seen this before).
'af'+'fair'='AFFAIR'
(Other definitions for affair that I've seen before include "Amour" , "Thing to be done with raffia" , "Involvement" , "Secret sexual relationship" , "Matter or concern, perhaps of the heart" .)