Turn victory to defeat at the outset (4)
I believe the answer is:
wind
'turn' is the definition.
(thesaurus)
'victory to defeat at the outset' is the wordplay.
'victory' becomes 'win' (I've seen this before).
'to' is a charade indicator (letters next to each other).
'at the outset' says to take the initial letters.
The first letter of 'defeat' is 'd'.
'win'+'d'='WIND'
(Other definitions for wind that I've seen before include "Move on a twisting path" , "Curl sinuously" , "See 7" , "Turn; current" , "Meaningless talk; twist" .)