Display burden on one vehicle (3,4)
I believe the answer is:
air taxi
'vehicle' is the definition.
(I've seen this before)
'display burden on one' is the wordplay.
'display' becomes 'air' (I've seen this before**).
'burden' becomes 'tax' (I've seen this before).
'on' means one lot of letters go next to another.
'one' becomes 'i' (Roman numeral).
'air'+'tax'+'i'='AIR TAXI'
(Other definitions for air taxi that I've seen before include "Small aircraft for hire" , "transport" , "Vehicle" , "One's flown commercially" .)