Champion branded Sartre a drunk (8-6)
I believe the answer is:
standard-bearer
'champion' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'branded sartre a drunk' is the wordplay.
'drunk' is an anagram indicator.
'branded'+'sartre'+'a'='brandedsartrea'
'brandedsartrea' anagrammed gives 'STANDARD-BEARER'.
Can you help me to learn more?
(Other definitions for standard-bearer that I've seen before include "Leading figure in a cause" , "Leading figure in a movement" , "Leader of a cause" , "Flag-carrying soldier" .)