Carriage seen in April and August (6)
I believe the answer is:
landau
'carriage' is the definition.
(type of horse-drawn carriage)
'in april and august' is the wordplay.
'in' indicates a hidden word.
'LANDAU' is hidden within 'april and august'.
'seen' acts as a link.
(Other definitions for landau that I've seen before include "Old-fashioned four-wheeled covered carriage" , "Transport" , "A four-wheel covered carriage" , "Horse-drawn, folded-top carriage" , "Four-wheeled vehicle with two folding hoods" .)