Drink, say, before gong used (6)
I believe the answer is:
eggnog
'drink' is the definition.
(eggnog is a kind of drink)
'say before gong used' is the wordplay.
'say' becomes 'eg'.
'before' says to put letters next to each other.
'used' indicates an anagram.
'gong' anagrammed gives 'gnog'.
'eg'+'gnog'='EGGNOG'
(Other definitions for eggnog that I've seen before include "Festive dairy beverage" , "Dairy-based drink" , "Milky winter punch" , "spirits in me?" , "Christmas tipple" .)