Fermented apple juice (5)
I believe the answer is:
cider
'fermented apple juice' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for cider that I've seen before include "Apple-based drink" , "Drink made from fermented apples" , "Scrumpy" , "Alcoholic drink from fermented apple juice" , "Pear drink" .)