Product of fine season (9)
I believe the answer is:
offspring
'product' is the definition.
(thesaurus)
'of fine season' is the wordplay.
'fine' becomes 'f' (abbreviation).
'season' becomes 'spring' (spring is a kind of season).
'of'+'f'+'spring'='OFFSPRING'
(Other definitions for offspring that I've seen before include "Child" , "Kids" , "Issue for raising" , "Progeny" , "seed" .)