To create internal clan games, it would be easier if you could directly invite your clan members in the invitation menus.

If you're in a bigger clan and you don't want to add all 100 members to your friends list, you have to invite every single players laboriously by using the "search" tab. A new invitation tab which shows only your clan members, similar to the friends tab, but maybe with filter options like "rank" or "level" would be the ideal solution.