Coming out on top - very treacherous in winter around hill (7)
I believe the answer is:
'coming out on top' is the definition.
'very treacherous in winter around hill' is the wordplay.
'very' becomes 'v' (abbreviation).
'treacherous in winter' becomes 'icy' (treacherous can mean dangerous).
'around' means one lot of letters goes inside another.
'hill' becomes 'tor' (tor is a kind of hill).
'icy' enclosing 'tor' is 'ictory'.
(Other definitions for victory that I've seen before include "Success in a contest" , "See 8" , "Triumph" , "Opposite of defeat" , "old naval vessel" .)