Counterpart has tip-top victory (4)
I believe the answer is:
twin
'counterpart' is the definition.
(I know that counterpart can be written as twin)
'tip-top victory' is the wordplay.
'tip-top' becomes 't' (top of the word 'tip-').
'victory' becomes 'win' (a win is a victory).
't'+'win'='TWIN'
'has' is the link.
(Other definitions for twin that I've seen before include "One of two conceived together" , "Castor or Pollux?" , "Very much like" , "One of two conceived simultaneously" , "Romulus or Remus" .)