Clams are provided by the company that supplies the ads and offers, Tapjoy. After you complete a goal for clams, it may take some time for the ad company to verify that you have fulfilled the requirement and to deliver the reward to your account.
In the meantime, you can contact the ad company for more assistance. If you're unsure how to contact them, you can visit this page for further guidelines: http://tapjoy.force.com/
In the meantime, you can contact the ad company for more assistance. If you're unsure how to contact them, you can visit this page for further guidelines: http://tapjoy.force.com/