Upset gentleman resubmitted content using pseudonym (8)
I believe the answer is:
username
'pseudonym' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'upset gentleman resubmitted content' is the wordplay.
'upset' says the letters should be written backwards.
'content' indicates the answer is hidden within the clue (letters contained within the clue).
'emanresu' is hidden within 'gentleman resubmitted'.
'emanresu' written backwards gives 'USERNAME'.
'using' is the link.
Can you help me to learn more?
(Other definitions for username that I've seen before include "One's identifier on a computer" , "Person's computer ID" , "Login ID" , "Log in identifier" , "Electronic identity" .)