Rota devised with a vital supplier (5)
I believe the answer is:
aorta
'vital supplier' is the definition.
(vital artery)
'rota devised with a' is the wordplay.
'devised with' indicates an anagram.
'rota' mixed up with 'a' gives 'AORTA'.
(Other definitions for aorta that I've seen before include "Main artery of body" , "Major blood vessel" , "Main human artery" , "Vital blood vessel" , "Trunk artery from the heart" .)