Drink to a royal uprising (5)
I believe the answer is:
lager
'drink' is the definition.
(lager is a kind of drink)
'royal uprising' is the wordplay.
'royal' becomes 'regal' (synonyms).
'uprising' says the letters should be written backwards.
'regal' backwards is 'LAGER'.
'to a' acts as a link.
(Other definitions for lager that I've seen before include "African camp" , "Drink - 5 down (anag)" , "Pilsner, for example" , "A regal sort of drink" , "Effervescent beer" .)