Train — bus (5)
I believe the answer is:
coach
This clue is a double definition.
'train' is the first definition.
(I know that coach is a action)
'bus' is the second definition.
(I know that bus can be written as coach)
(Other definitions for coach that I've seen before include "Trainer and train carriage" , "Tutor" , "Instruct" , "Railway carriage or sports instructor" , "Train - or part of one!" .)