A rota arranged for distribution of blood supplies (5)
I believe the answer is:
aorta
'distribution of blood supplies' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'a rota arranged' is the wordplay.
'arranged' indicates anagramming the letters.
'rota' with letters rearranged gives 'orta'.
'a'+'orta'='AORTA'
'for' is the link.
Can you help me to learn more?
(Other definitions for aorta that I've seen before include "One leads from heart" , "Trunk route" , "This carries blood from the heart" , "Heart's great artery" , "main arterial route" .)