Knocked back excellent beer - splendid stuff! (7)
I believe the answer is:
regalia
'splendid stuff' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe there's an association between them I don't understand?
'knocked back excellent beer' is the wordplay.
'knocked back' shows that the letters should be reversed in order.
'excellent' becomes 'ai' (resembles 'A1', old-fashioned term for excellent).
'beer' becomes 'lager' (type of beer).
'ai'+'lager'='ailager'
'ailager' back-to-front 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" .)