Argentine president winning is not half a character (7)
I believe the answer is:
persona
'character' is the definition.
(I know that character can be written as persona)
'argentine president winning is not half a' is the wordplay.
'argentine president' becomes 'Peron' (Juan Peron, former Argentine president).
'winning' indicates putting letters inside (some letters win or obtain others).
'is not half' becomes 's' (I can't explain this - if you can you should give a lot more credence to this answer).
'peron' enclosing 's' is 'person'.
'person'+'a'='PERSONA'
Can you help me to learn more?
(Other definitions for persona that I've seen before include "No pears (anag.)" , "One's outward character" , "External aspect of character" , "One who is diplomatically acceptable" , "Role adopted by actor" .)