Trouper, playing loud man at National Theatre, leads in Zenda as "unconquered" villain (6,2,7)
I believe the answer is:
rupert of hentzau
'villain' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.
'trouper playing loud man at national theatre leads in zenda as unconquered' is the wordplay.
'playing' indicates an anagram.
'loud man at' becomes 'fhe' (I can't justify this - if you can you should give a lot more credence to this answer).
'national theatre' becomes 'NT' (abbreviation).
'leads in' suggests taking the first letters (I've seen 'lead in' mean this).
The first letters of 'zenda as unconquered' is 'zau'.
'trouper' with letters rearranged gives 'ruperto'.
'ruperto'+'fhe'+'nt'+'zau'='RUPERT OF HENTZAU'
Can you help me to learn more?
(Another definition for rupert of hentzau that I've seen is " literary hero".)