It goes down well as one of the Elgar Variations (5)
I believe the answer is:
lager
'it goes down well as one of' is the definition.
The definition suggests a singular noun which matches the answer.
'elgar variations' is the wordplay.
'variations' is an anagram indicator.
'elgar' anagrammed gives 'LAGER'.
'the' acts as a link.
Can you help me to learn more?
(Other definitions for lager that I've seen before include "A regal sort of drink" , "Type of beer" , "The drink could be regal" , "Regal kind of beer" , "Tipple" .)