Clandestine, thought up by MaskedManClaus, was during the time the users Kalasta, Jagyel, and Lumiv weren't debunked to be TolfTolf. This plan was discussed for a while until it was claimed that TolfTolf had been killed by Kalasta. Clandestine was about MaskedManClaus going under to the Ivichs side to gather information because the three users were accounted as Ivichs during the time.
MaskedManClaus said his plan was to type up convincing requests and plans to the Ivichs (which had no meaning) and work his way in. From there, he would see what the plans were and would report back to others on what's going on so the Venkons would be one step ahead of the game.
While none of it was convincing enough for Kalasta, the plan was halted and discarded since it seemed to be going nowhere. It wasn't bothered to be pushed with, as the situation began to die down. And after it was found that TolfTolf had been playing everybody, Clandestine was seen more as a waste of effort and time to everyone.
The plan that was thought to be useless was put into action. All of Claus's betrayal was Clandestine being used for once. His betrayal can be explained on 2/11/16: Claus's Treason. To understand when and how it was used, read Saved Logs: Claus's Comeback.