Joker riding cart (5)
I believe the answer is:
wagon
'cart' is the definition.
(thesaurus)
'joker riding' is the wordplay.
'joker' becomes 'wag' (I've seen this before).
'riding' becomes 'on' (I've seen this in other clues).
'wag'+'on'='WAGON'
(Other definitions for wagon that I've seen before include "Horse-drawn vehicle" , "Wild West trail vehicle?" , "Four-wheeled goods vehicle" , "Transport" , "Vehicle carrying goods" .)