Do business to preserve many vehicles (7,3)
I believe the answer is:
traffic jam
'do' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'business to preserve many vehicles' is the wordplay.
I cannot quite see how this works, but
'business' could be 'traffic' (I've seen this before) and 'traffic' is located in the answer.
'preserve' could be 'jam' (jam is a kind of preserve) and 'jam' is present in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for traffic jam that I've seen before include "Vehicular snarl-up" , "It causes a hold-up" , "Gridlock" , "Problem, in a way" , "Bottleneck on wheels" .)