Keep shaking the cart (5)
I believe the answer is:
wagon
'cart' is the definition.
(I've seen this in another clue)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for wagon that I've seen before include "On this, one keeps dry!" , "Railway freight vehicle" , "Wild West trail vehicle?" , "Transport" , "Van, lorry" .)