A vehicle that's trying to run somebody down? (7)

I believe the answer is:

trailer

I'm a little stuck... Click here to teach me more about this clue!

'a vehicle' is the definition.
(trailer is a kind of vehicle)

I don't understand the rest of the clue.

(Other definitions for trailer that I've seen before include "ground plant" , "It's pulled by a vehicle" , "vehicle without power" , "Vehicle hauled by car or truck" , "Short scenes from a future film" .)

I've seen this clue in the Evening Standard.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.