A rota devised for vital supplier (5)
I believe the answer is:
aorta
'vital supplier' is the definition.
(vital artery)
'a rota devised' is the wordplay.
'devised' indicates an anagram.
'rota' anagrammed gives 'orta'.
'a'+'orta'='AORTA'
'for' is the link.
(Other definitions for aorta that I've seen before include "claret supplier" , "Great artery in body" , "main arterial route" , "Main route from the heart" , "Main arterial vessel, carrying blood to the heart" .)