What succeeds uniform winner (6)
I believe the answer is:
victor
This clue is a double definition.
'what succeeds uniform' is the first definition.
(phonetic alphabet whisky, uniform, victor)
'winner' is the second definition.
(I know that winner can be written as victor)
(Other definitions for victor that I've seen before include "whiskey after this" , "''To the . . . . . . the spoils'' (6)" , "Oh dear!" , "winning player" , "The one who wins the battle" .)