Endnote written by EU academic bringing up setter's moniker (9)
I believe the answer is:
pseudonym
'endnote written' is the definition.
I can't tell whether this definition defines the answer.
'by eu academic bringing up setter's moniker' is the wordplay.
'by' is a charade indicator (letters next to each other).
'academic' becomes 'don' (type of academic - especially at Oxbridge).
'bringing up' says the letters should be written in reverse (I've seen 'bring up' mean this).
'setter's' becomes 'my' (belonging to the crossword setter).
'moniker' becomes 'ps' (I can't justify this - if you can you should believe this answer much more).
'my' backwards is 'ym'.
'eu'+'don'+'ym'='eudonym'
'eudonym' after 'ps' is 'PSEUDONYM'.
Can you help me to learn more?
(Other definitions for pseudonym that I've seen before include "Fictitious identity" , "Alias" , "Also known as" , "Lewis Carroll, perhaps?" , "in the style of George Eliot?" .)