One said to have been successful (3)
I believe the answer is:
won
'have been successful' is the definition.
I can't judge whether this definition defines the answer.
'one said' is the wordplay.
'said' shows a homophone (sound like).
'one' is a homophone of 'WON'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for won that I've seen before include "and 26: Chinese dumpling" , "Triumphed" , "Gained a victory" , "prevailed" , "Came first" .)