Police officer at home with eyewitness checking out a Tesla (9)
I believe the answer is:
inspector
'police officer' is the definition.
(inspector is a kind of police officer)
'home with eyewitness checking out a tesla' is the wordplay.
I cannot quite see how this works, but
'home' could be 'in' ('he's home' can mean 'he's in') and 'in' is found in the answer.
'tesla' could be 't' (scientific unit) and 't' is located in the answer.
This explanation may well be incorrect...
'at' acts as a link.
Can you help me to learn more?
(Other definitions for inspector that I've seen before include "bluebottle!" , "leading rank" , "auditor" , "Police officer" , "Examining official" .)