So far, the clan is only made for having fun etc, but what if we made it a bit realistic? The lower classes work for the higher classes, and the higher classes works for the boss.
Missions can be given to all classes underneath you, like killing a certain player, gather a certain amount of money for someone, robbing a bank (or even someone) etc etc.
By adding these missions you can make sure that only the MOST active players can stay in the clan and those who's not active, gets kicked out.
When the boss thinks you've done good enough you get promoted to the next class.