Working under clown car (5)
I believe the answer is:
wagon
'car' is the definition.
(wagon is a kind of car)
'working under clown' is the wordplay.
'working' becomes 'on' (on can mean working or activated).
'under' says to put letters next to each other.
'clown' becomes 'wag' (I can't justify this - if you can you should believe this answer much more).
'on' after 'wag' is 'WAGON'.
Can you help me to learn more?
(Other definitions for wagon that I've seen before include "On this, one keeps dry!" , "Vehicle for transporting goods" , "Wild West trail vehicle?" , "Railway freight vehicle" , "Van, lorry" .)