Virginia must stop dog -- it's hard work (7)
I believe the answer is:
travail
'hard work' is the definition.
(travail can mean hard work or effort)
'virginia must stop dog' is the wordplay.
'virginia' becomes 'va' (US state abbreviation).
'must stop' indicates putting letters inside (stopping can mean blocking a gap).
'dog' becomes 'trail' (both can mean to follow).
'va' placed inside 'trail' is 'TRAVAIL'.
'it's' is the link.
(Other definitions for travail that I've seen before include "Painful labour" , "Labour, toil" , "Painful or laborious effort, like childbirth" , "Toil - anguish" , "painful exercise" .)