Temperance society conceals unopened wine vessel (5)
I believe the answer is:
aorta
'vessel' is the definition.
(blood vessel)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for aorta that I've seen before include "Principal artery" , "Blood-carrier from a heart" , "Trunk artery from the heart" , "Main arterial vessel, carrying blood to the heart" , "Main artery of body" .)