Be successful for first half of season (3)
I believe the answer is:
win
'be successful' is the definition.
(I've seen this before)
'first half of season' is the wordplay.
'first half of' means to take half the letters.
'season' becomes 'winter' (winter is a season).
'winter' halved is 'WIN'.
'for' acts as a link.
(Other definitions for win that I've seen before include "Achieve victory" , "Come first" , "Come out on top" , "Trumph" , "Be successful" .)