Autumnal quaff (5)
I believe the answer is:
cider
'autumnal quaff' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for cider that I've seen before include "Apple-based drink" , "Apple-based beverage" , "Alcoholic drink (to be taken with Rosie?)" , "Alcoholic drink made from apples" , "Drink made from pears" .)