He presumably has winning ways (6)
I believe the answer is:
victor
'he presumably has winning ways' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'he presumably' is the wordplay.
'he' becomes 'Vic' (short for Victor).
'presumably' becomes 'tor' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'vic'+'tor'='VICTOR'
Can you help me to learn more?
(Other definitions for victor that I've seen before include "The . . . . . . comic with Alf Tupper" , "Comms code for V" , "whiskey after this" , "The one who wins the battle" , "One coming out on top" .)