. . . where vehicle hits edge of pothole: complain! (4)
I believe the answer is:
carp
'complain' is the definition.
(carp can informally mean to complain or whinge)
'where vehicle hits edge of pothole' is the wordplay.
I cannot really see how this works, but
'vehicle' could be 'car' (car is a kind of vehicle) and 'car' is found within the answer.
A single letter 'p' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for carp that I've seen before include "Nagging fish?" , "Go on at" , "Cavil - fish" , "Keep complaining" , "Continually nag; fish" .)