On which people clean their feet when in a hurry? (4,4)

'on which people clean their feet when in a hurry?' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.

'on which people clean their feet when in a hurry?' is the wordplay.
I cannot really see how this works, but
'on' could be 'at' (I've seen this in other clues) and 'at' is found in the answer.
'hurry?' could be 'rush' ('rush' can be a synonym of 'hurry') and 'rush' is found in the answer.
The remaining letters 'ms' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?