Popular 3rd party Instagram client 6Tag got updated to v3.0 in Windows Phone Store. The updated app now includes the support for the new Instagram Direct feature. Instragram Direct allows you to send photos privately to other Instagram users. You can now view direct messages and get notifications of new messages, also you can now comment and respond to direct messages you receive. This update also includes some minor UI changes to improve overall experience.
Download it here from Windows Phone Store here.