Ha, what i would suggest is looking in the mirror. Use some of your lines, come up with nuances and character traits. It will help give you a gist for the costume. My costume originally was striped footy pajama's with a ringmasters jacket. I wuold suggest going through normal costume websites, seeing what they have, and either using that or put your own spin on it. Like for a normal clown jumpsuit, cut it in half. Use suspenders and a straight jacket. Thats my other clown character, call him Freakshow. Just go through trial and error, i doubt you will get it right on the first try, but if you do, congrats! Ha