Devise a rota for vital supplier (5)
I believe the answer is:
aorta
'vital supplier' is the definition.
(vital artery)
'devise a rota' is the wordplay.
'devise' is an anagram indicator (I've seen 'devised' mean this).
'a'+'rota'='arota'
'arota' is an anagram of 'AORTA'.
'for' is the link.
(Other definitions for aorta that I've seen before include "Body's main artery" , "Trunk route" , "main arterial route" , "Great artery in body" , "Major blood vessel" .)