Great arterial way (5)

I believe the answer is:

aorta

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'great arterial way' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.

This is the entire clue.

Can you help me to learn more?

(Other definitions for aorta that I've seen before include "vital transporter" , "it's drawing blood!" , "Main artery of body" , "Blood-carrier from a heart" , "Blood carrier" .)

I've seen this clue in The Globe and Mail.

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