Windward island bans that French cocktail (7)
I believe the answer is:
martini
'cocktail' is the definition.
(martini is a kind of cocktail)
'windward island bans that french' is the wordplay.
'windward island' becomes 'martinique' (I've seen this in another clue).
'bans' is a deletion indicator.
'that french' becomes 'que' (French for 'that').
'martinique' with 'que' taken away is 'MARTINI'.
(Other definitions for martini that I've seen before include "In glass, one's dry" , "Gin or vodka with dry vermouth" , "Cocktail made with gin or vodka and vermouth" , "Type of Italian vermouth" , "obtained from a bottle" .)