Drink instant tea (5)
I believe the answer is:
mocha
'drink' is the definition.
(mocha is a kind of drink)
'instant tea' is the wordplay.
'instant' becomes 'mo'.
'tea' becomes 'cha' (cha is a type of tea).
'mo'+'cha'='MOCHA'
(Other definitions for mocha that I've seen before include "Leather" , "Dark brown" , "Kind of coffee" , "Arabian coffee" , "Coffee drink" .)