Brahms and Liszt agree with poor chap off to Bayreuth (9)
I believe the answer is:
operagoer
'chap off to bayreuth' is the definition.
I can't tell whether this defines the answer.
'brahms and liszt agree with poor' is the wordplay.
'brahms and liszt' indicates an anagram (Cockney rhyming slang for 'pissed', i.e. drunk).
'with' is a charade indicator (letters next to each other).
'agree' after 'poor' is 'pooragree'.
'pooragree' is an anagram of 'OPERAGOER'.
Can you help me to learn more?
(Other definitions for operagoer that I've seen before include "One attending, eg, Covent Garden" , "One enjoying Carmen, say" , "attender of musical performances" , "One attending music theatre" .)