Four-wheeled carriage (6)
'four-wheeled carriage' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for landau that I've seen before include "Horse-drawn, folded-top carriage" , "Transport" , "Old four-wheeled covered carriage" , "A four-wheel covered carriage" , "Old-fashioned four-wheeled covered carriage" .)
(Other definitions for phaeton that I've seen before include "4-wheeled carriage" , "Coach" , "transport" .)