Centre of circulation (5)
I believe the answer is:
heart
This clue could be a double definition.
'centre' is the first definition.
(I know that centre can be written as heart)
'circulation' is the second definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'of' is the link.
Can you help me to learn more?
(Other definitions for heart that I've seen before include "Centre; valour" , "Player for Scottish team" , "It's in the chest" , "Centre; core" , "Spirit - core" .)