With younger players, the lure of the ball often leads to players bunching up and swarming around it. You want your players to support each other, but it needs to be effective support. That is support players taking a pass while moving onto the ball and running at space.
Obstacle Course
Instead of running normal straight line passing drills, try this.
Set up a channel with some obstacles in it. You can use tackle pads, contact pads, poles, markers or anything else which comes to hand. The players have to run and pass while avoiding all the obstacles. The ball must be handled by every player in the group before the end of the channel.

If you find some players are reluctant to pass, put cones at intervals down each side. Each ball carrier then has to pass before reaching the next cone.
You can add a competitive element to the drill if you time each group from receiving the ball to scoring at the far end.
Passing Zones
Using zones can help keep players in certain parts of the pitch. Coaching these skills is a process which takes time to develop.

In this drill there are four attackers and two defenders. The defenders can move in any direction to any part of the practice area. The attackers have to stay in their zone, but can pass and run. This will help maintain space between the attacking players, but may lead to a lot of passing with little go forward. To develop go forward skills, allow each attacking player to move one zone left or right.
Possible quick fix
By playing the best player out wide on the wing, it’s an incentive for his team mates to get the ball out to him, thus creating width and a bit of space.