Drink reserved, also bottled (6)
I believe the answer is:
shandy
'drink' is the definition.
(shandy is a kind of drink)
'reserved also bottled' is the wordplay.
'reserved' becomes 'shy' (I've seen this in other clues).
'also' becomes 'and' (I've seen this before).
'bottled' means one lot of letters goes inside another (to bottle can mean contain).
'shy' going around 'and' is 'SHANDY'.
(Other definitions for shandy that I've seen before include "Beer/lemonade drink" , "Weakly-alcoholic drink" , "Beer-lemonade mix" , "Drink made of beer and lemonade" , "Alcohol" .)