Transfer gains ground around start of season (6)
I believe the answer is:
assign
'transfer' is the definition.
(assigning is a kind of transfering)
'gains ground around start of season' is the wordplay.
'ground' indicates an anagram ('grind' the letters into a new form).
'around' means one lot of letters goes inside another.
'start of' suggests taking the first letters.
The initial letter of 'season' is 's'.
'gains' is an anagram of 'asign'.
'asign' placed around 's' is 'ASSIGN'.
(Other definitions for assign that I've seen before include "(Of a job) allocate to someone" , "Allocate (duties to someone)" , "Allot, allocate" , "Detail" , "award" .)