Splendid beer served up (5)
I believe the answer is:
regal
'splendid' is the definition.
(thesaurus)
'beer served up' is the wordplay.
'beer' becomes 'lager' (lager is a kind of beer).
'served up' shows that the letters should be reversed in order.
'lager' written backwards gives 'REGAL'.
(Other definitions for regal that I've seen before include "Magnificent, dignified" , "Like a queen?" , "Befitting a monarch" , "Kingly glare?" , "Fit for a monarch" .)