Energy drink (6)
I believe the answer is:
spirit
I believe this clue is a double definition.
'energy' is the first definition.
(I've seen this before)
'drink' is the second definition.
(I've seen this in other clues)
(Other definitions for spirit that I've seen before include "Liveliness - hard liquor" , "Life force" , "Ghost or animation" , "Courage, determination" , "Spectre - alcohol" .)