Drink royal’s taken up (5)
I believe the answer is:
lager
'drink' is the definition.
(lager is a kind of drink)
'royal's taken up' is the wordplay.
'royal' becomes 'regal' (synonyms).
'taken up' shows that the letters should be reversed in order.
'regal' reversed gives 'LAGER'.
(Other definitions for lager that I've seen before include "Light-bodied beer" , "Regal kind of beer" , "A regal sort of drink" , "Effervescent beer" , "A brew" .)