Good school subject to follow in French class (5)
I believe the answer is:
genre
'class' is the definition.
(genre can mean a class or type)
'good school subject to follow in french' is the wordplay.
'good' becomes 'g' (abbreviation).
'school subject' becomes 'RE' (Religious Education).
'to follow' is a charade indicator (letters next to each other).
'in french' becomes 'en' ('in' in French).
're' after 'en' is 'enre'.
'g'+'enre'='GENRE'
(Other definitions for genre that I've seen before include "Category of literature" , "Literary type, species" , "Particular style of art or literature, may be green" , "Style/category of art" , "Style (of art/literature)" .)