War later developed behind quarry - it's drink (7,5)
I believe the answer is:
mineral water
'drink' is the definition.
(I know that mineral water is a type of drink)
'war later developed behind quarry' is the wordplay.
'developed' indicates an anagram.
'behind' is a charade indicator (letters next to each other).
'quarry' becomes 'mine' (type of mine).
'war'+'later'='warlater'
'warlater' is an anagram of 'ralwater'.
'ralwater' put after 'mine' is 'MINERAL WATER'.
'it's' acts as a link.
(Other definitions for mineral water that I've seen before include "Drink with natural salts" , "Sparkler" , "Still or sparkling?" .)