The idea is that each day there is a new objective for clans.
These objectives are things like: Donate 1k troops, Destroy 100 Mortars, Raid 5mill gold/elixir... Etc, these are just examples.
Any actions by each of the clan member will contribute to these and so it focuses on the whole clan working together to achieve them as they are designed to be out of the reach of individuals.
Ok the objective will have a reward for the whole clan, these will range from: collectors auto boosting for a day, troop training speed doubled for the day/few hours, a bonus of loot, clan XP and possibly more...
Perhaps the difficultly of the objective could be decided by the amount of clan members, the average TH levels, the trophy count.
These would be refreshed each day for the clan to participate for.
I didn't know of it previously, thanks for showing me.
I think a lot of members want more co-operation and teamwork within the clans on a daily basis, after all the game is clan wars. I don't think there is much areas for teamwork to be used apart from clan wars.