Vessel seen in Victoria or Tasmania (5)
I believe the answer is:
aorta
'vessel' is the definition.
(blood vessel)
'in victoria or tasmania' is the wordplay.
'in' says the answer is hidden in the clue.
'AORTA' is hidden in the letters of 'victoria or tasmania'.
'seen' acts as a link.
(Other definitions for aorta that I've seen before include "Large trunk artery" , "main arterial route" , "Blood-carrier from a heart" , "One leads from heart" , "Tube" .)