Tut … was so heartlessly given a penalty on quiet motorway (9)

I believe the answer is:
mummified
'tut was so heartlessly given a penalty' is the definition.
I can't judge whether this definition defines the answer.
'quiet motorway' is the wordplay.
I cannot really see how this works, but
'quiet' could be 'mum' (to keep mum is to stay quiet) and 'mum' is present in the answer.
'motorway' could be 'mi' (resembles M1, English motorway) and 'mi' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'on' acts as a link.
Can you help me to learn more?
(Another definition for mummified that I've seen is " dried up".)
