United were victorious reportedly (3)
I believe the answer is:
one
'united' is the definition.
(as in a phrase like 'we are one')
'were victorious reportedly' is the wordplay.
I cannot really understand how this works, but
'reportedly' could be 'e' (I've seen this in other clues) and 'e' is found in the answer.
The remaining letters 'on' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for one that I've seen before include "Unity" , "doesn't count for much" , "joke" , "time" , "Leading cardinal" .)