Crowd travelled by car (5)
I believe the answer is:
drove
I believe this is a double definition.
'crowd' is the first definition.
(drove is a kind of crowd)
'travelled by car' is the second definition.
(I've seen this before)
(Other definitions for drove that I've seen before include "Moving flock; forced" , "Took car; herd animals" , "Flock of animals being driven" , "compelled to work excessively" , "Number of cattle" .)