Follow, acquiring a victory that's hard work (7)
I believe the answer is:
travail
'hard work' is the definition.
(travail can mean hard work or effort)
'follow acquiring a victory' is the wordplay.
'follow' becomes 'trail' (trail can mean to follow in secret).
'acquiring' is an insertion indicator.
'victory' becomes 'v'.
'a'+'v'='av'
'trail' going around 'av' is 'TRAVAIL'.
'that's' acts as a link.
(Other definitions for travail that I've seen before include "Painful labour" , "painful exercise" , "Hard labour" , "Old word for pangs of childbirth" , "In old use, the pains of childbirth" .)