Minute Cryptic

This clue is an &lit meaning that the whole clue is both wordplay and definition. So, our answer here will be a kind of vehicle that's typically found behind another vehicle.

This clue's indicator is 'behind', which is so simple that it's almost not really an indicator in its own right. We sometimes call it a repositioning indicator, and it tells us to put one chunk of fodder on the other side or another chunk. About half of solvers will consider text on the left to be 'behind' text on the right, and the other half will think the opposite. Regardless, it's usually safe to assume in cryptics that it's guiding you to swap the order of two chunks of fodder.

This clue's fodder is 'A', 'vehicle', and 'another vehicle!'. We'll put 'A' directly in our answer with no changes, and then we'll need to find substitutes for 'vehicle' and 'another vehicle'. 'another' here is really telling us that we'll need to find different substitutes for 'vehicle' and 'vehicle' (not the same substitute twice).