Caution ex-PM, cycling on motorway in front of Tesla (8)

I believe the answer is:
mistrust
'caution' is the definition.
The definition and answer can be both human attributes as well as being singular nouns.
Perhaps there's a link between them I don't understand?
'ex-pm cycling on motorway in front of tesla' is the wordplay.
I cannot really see how this works, but
'motorway' could be 'mi' (resembles M1, English motorway) and 'mi' is found within the answer.
'tesla' could be 't' (scientific unit) and 't' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for mistrust that I've seen before include "Have no confidence in (someone)" , "Have doubts about" , "Regard with suspicion" , "reservations" , "Lack of belief (in someone)" .)