Possibly remain, left behind for a drink (7)
I believe the answer is:
mineral
'a drink' is the definition.
(I've seen this before)
'possibly remain left behind' is the wordplay.
'possibly' indicates an anagram.
'left' becomes 'l' (common abbreviation).
'behind' says to put letters next to each other.
'remain' with letters rearranged gives 'minera'.
'minera'+'l'='MINERAL'
'for' is the link.
(Other definitions for mineral that I've seen before include "Mined substance" , "What drink is available in ground" , "Zinc or magnesium, say" , "Ore; soft drink" , "ore, possibly" .)