Labour scent seizing a victory (7)
I believe the answer is:
travail
'labour' is the definition.
(travail is a kind of labour)
'scent seizing a victory' is the wordplay.
'scent' becomes 'trail' (I've seen this before).
'seizing' means one lot of letters goes inside another.
'victory' becomes 'v'.
'a'+'v'='av'
'trail' enclosing 'av' is 'TRAVAIL'.
(Other definitions for travail that I've seen before include "In old use, the pains of childbirth" , "Hard work" , "Old word for pangs of childbirth" , "Use of physical or mental energy; excessive labour..." , "Exertion, elbow grease" .)