Dispatch snow vehicle, we hear (4)
I believe the answer is:
slay
'dispatch' is the definition.
('slay' can be a synonym of 'dispatch')
'snow vehicle we hear' is the wordplay.
'snow vehicle' becomes 'sleigh' (I've seen this before).
'we hear' shows a homophone (sound like).
'sleigh' sounds like 'SLAY'.
(Other definitions for slay that I've seen before include "Butcher" , "Massacre" , "Kill (literary)" , "Destroy" , "Fatally hit" .)