Sure winner Ken found drunk in pub (6)
I believe the answer is:
banker
'sure winner' is the definition.
(I've seen this before)
'ken found drunk in pub' is the wordplay.
I cannot quite see how this works, but
an anagram of 'ken' is 'nke' which is present in the answer.
'pub' could be 'bar' (both are drinking establishments) and 'bar' is present in the leftover letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for banker that I've seen before include "Plane changing course maybe" , "one providing cash" , "Money man (or woman)" , "City worker?" , "A supposedly certain bet" .)