Sophisticate, person on brink of victory? One's lost! (3,5,4)
I believe the answer is:
man about town
'sophisticate' is the definition.
(thesaurus)
'person on brink of victory? one's lost' is the wordplay.
I cannot quite understand how this works, but
'person' could be 'abo' (Abo is an example) and 'abo' is found within the answer.
'of' could be 'o' and 'o' is located in the answer.
'one' could be 'an' (an apple is one apple) and 'an' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for man about town that I've seen before include "Dandy" , "Sophisticated socialite" , "He's fashionable and sophisticated" , "Fashionable sophisticate" , "Fashionable fellow" .)