When you are in a Clan, you can help your clan mates to speed up their crates or be helped!
This is really simple: your Clan mates (or you) will ask for help to open a Crate or Toolbox they are waiting to unlock at that moment. Each member that taps on it will reduce the timer by 3 minutes! So, the more Clan members helping, the quicker they will be able to open it!
Also, for every speed up you do (keep in mind that it's only one per box) you'll get 5 coins. This way, not only will you help your friends but also get yourself some currencies! Isn't that cool?
To be able to ask for help, you just have to tap on the crate you want to open and then on "Ask for Help".