Assume a pushup position, lower yourself to the ground in a controlled manner. On your way up push as hard and explosive as you can. Do this so that your hands actually come off of the ground, while in the air clap your hands together. After clapping, spread your hands back out, catch yourself and repeat the movement.
If you cannot do at least 20 pushups we suggest you do not even try this move. You could hurt yourself by not brining your hands back to the correct position and end up smashing your face!