How to get students attention after group work

Working in groups does have many advantages, but it also has its disadvantages. Working in groups is a very loud and tasking project for the teacher to take on. One of the methods I used to reign in the students is I simply clap and raise my hand. When the other students here my clap, the follow by clapping and raising their hand as well. We wait with our hand in the air until all the students are looking my way and quiet.