A youngster rejected fame without disagreement (2,3,3)
I believe the answer is:
as one man
'fame without disagreement' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.
'a youngster rejected' is the wordplay.
'youngster' becomes 'son' (a child).
'rejected' becomes 'eman' (I can't justify this - if you can you should give a lot more credence to this answer).
'a'+'son'+'eman'='AS ONE MAN'
Can you help me to learn more?
(Other definitions for as one man that I've seen before include "in concert" , "all agreed" , "All together in unison - males only" , "Unanimously" , "arguably sexist in Unison" .)