Despatch vessel (4)
I believe the answer is:
ship
This might be a double definition.
'despatch' is the first definition.
The definition and answer can be both to do with motion as well as being verbs in their base form.
Maybe you can see an association between them that I can't see?
'vessel' is the second definition.
(ship is a kind of vessel)
Can you help me to learn more?
(Other definitions for ship that I've seen before include "Sea-going craft" , "Navigable vessel" , "Large boat, dispatch" , "Large sailing vessel" , "eg QE2" .)