Bonnet-wearing drivers? (7)
I believe the answer is:
engines
'drivers?' is the definition.
The answer and definition can be both man-made objects as well as being plural nouns.
Perhaps you can see an association between them that I can't see?
'bonnet-wearing' is the wordplay.
I cannot quite understand how this works, but
'wearing' could be 'in' (you are 'in' the clothes you're wearing) and 'in' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for engines that I've seen before include "Powerful machines" , "Machines that convert power into motion" , "Locomotives" , "Motors" .)