Vehicle in Belgium and America (3)
I believe the answer is:
bus
'vehicle' is the definition.
(bus is a kind of vehicle)
'belgium and america' is the wordplay.
'belgium' becomes 'B' (international vehicle registration code).
'and' says to put letters next to each other.
'america' becomes 'us' (United States).
'b'+'us'='BUS'
'in' is the link.
(Other definitions for bus that I've seen before include "eg Double-decker" , "Use transport" , "Public transport vehicle" , "Of projectiles; (go) mad (slang)" , "Large passenger vehicle - small business!" .)