Run rings around unknown in the old city (3)

'run rings' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.

'around unknown in the old city' is the wordplay.
I cannot really see how this works, but
'around' could be 'o' (I've seen this in other clues) and 'o' is found in the answer.
'unknown' could be 'y' (algebra) and 'y' is located in the answer.
'old' could be 'o' (common abbreviation eg in OE for Old English) and 'o' is present in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?