Old four-wheeled covered carriage (6)
I believe the answer is:
landau
'old four-wheeled covered carriage' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for landau that I've seen before include "Old-fashioned four-wheeled covered carriage" , "An auld type of carriage" , "Old four-wheeled covered carriage" , "Horse-drawn, folded-top carriage" , "Four-wheeled horse-drawn carriage" .)