Gold on country carriage (6)
I believe the answer is:
landau
'carriage' is the definition.
(I've seen this before)
'gold on country' is the wordplay.
'gold' becomes 'au' (Au is the chemical symbol for gold**).
'on' means one lot of letters go next to another.
'country' becomes 'land' ('land' can be a synonym of 'country').
'au' put after 'land' is 'LANDAU'.
(Other definitions for landau that I've seen before include "Old four-wheeled covered carriage" , "Transport" , "Old-fashioned four-wheeled covered carriage" , "Horse-drawn, folded-top carriage" , "Horse-drawn carriage or car with folding top" .)