Traffic tickets are handled through the Clerk of Court Office. If you simply want to pay the ticket, and an appearance is not required, then you can either mail or bring the appropriate copy of the ticket, plus the fine, to the:
Clerk of Court Office
612 N 2nd Street
Clinton, IA 52732
If the ticket was issued outside the Clinton area, there should be a corresponding address for the local Clerk of Court Office near the top of the citation. Send the ticket, plus the fine, to that address.