Knocked back excellent beer - splendid stuff! (7)
I believe the answer is:
regalia
'splendid stuff' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps you can see a link between them that I don't see?
'knocked back excellent beer' is the wordplay.
'knocked back' says the letters should be written in reverse.
'excellent' becomes 'ai' (resembles 'A1', old-fashioned term for excellent).
'beer' becomes 'lager' (type of beer).
'ai'+'lager'='ailager'
'ailager' backwards is 'REGALIA'.
Can you help me to learn more?
(Other definitions for regalia that I've seen before include "Royal paraphernalia" , "Orb and sceptre etc" , "Finery" , "Crown jewels" , "Royal insignia" .)