Tankard filler (3)
I believe the answer is:
ale
'tankard filler' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ale that I've seen before include "The A in CAMRA" , "Beer consumed in chalets" , "Light-coloured beer" , "A drink; sounds like become ill" , "Booze" .)