Bus money (4)
I believe the answer is:
fare
'bus money' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for fare that I've seen before include "Food - money for travelling - get on" , "Grip (of a tyre)" , "Charge for travelling on train or bus" , "Cost of travel" , "(Person paying) price for travel" .)