Drink gallons, returning actual bottles (5)
I believe the answer is:
lager
'drink' is the definition.
(lager is a kind of drink)
'gallons returning actual bottles' is the wordplay.
'gallons' becomes 'g' (abbreviation).
'returning' is a reversal indicator.
'actual' becomes 'real' (similar in meaning).
'bottles' means one lot of letters goes inside another (bottle can mean to contain).
'real' reversed gives 'laer'.
'g' inserted within 'laer' is 'LAGER'.
(Other definitions for lager that I've seen before include "A regal sort of drink" , "Light-bodied beer" , "African camp" , "The drink could be regal" , "Type of beer" .)