Drink at marriage, endless bubbly (9)
I believe the answer is:
margarita
'drink' is the definition.
(margarita is a kind of drink)
'at marriage endless bubbly' is the wordplay.
'endless' means to remove the last letter.
'bubbly' is an anagram indicator.
'at'+'marriage'='atmarriage'
'atmarriage' with its final letter taken off is 'atmarriag'.
'atmarriag' with letters rearranged gives 'MARGARITA'.
(Other definitions for margarita that I've seen before include "Stiff drink" , "Type of tequila cocktail" , "Tequila/citrus cocktail" , "Tequila-based cocktail" , "Spanish girl" .)