Important match of French drink (7)
I believe the answer is:
decider
'important match' is the definition.
(I've seen this before)
'of french drink' is the wordplay.
'of french' becomes 'de' ('of' in French).
'drink' becomes 'cider' (cider is a kind of drink).
'de'+'cider'='DECIDER'
(Other definitions for decider that I've seen before include "Clinching game" , ""Golden goal", for example" , "Ultimate goal" , "Crucial final game" , "Extra period of play to settle a draw" .)