President's event in the velodrome (7)
I believe the answer is:
madison
'president's' is the definition.
(James Madison, fourth president of the USA)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for madison that I've seen before include "United States president -- Wisconsin's capital" , "James -, fourth president of the USA" , "dance?" , "State capital of Wisconsin" , "James, fourth US president" .)