Turn over a vehicle in the morning — it rattles! (6)
I believe the answer is:
Here is my best explanation:
'it rattles' is the definition.
'turn over a vehicle in the morning' is the wordplay.
'turn over' is a reversal indicator.
'vehicle' becomes 'car' (car is a kind of vehicle).
'in the morning' becomes 'am'.
'acaram' back-to-front is 'MARACA'.