Drink sovereign rejected (5)
I believe the answer is:
lager
'drink' is the definition.
(lager is a kind of drink)
'sovereign rejected' is the wordplay.
'sovereign' becomes 'regal'.
'rejected' is a reversal indicator.
'regal' back-to-front is 'LAGER'.
(Other definitions for lager that I've seen before include "Lout's drink?" , "Drink - 5 down (anag)" , "Tipple" , "African camp" , "Light-coloured beer" .)