What is the easiest way to send to movie clip to the background?

Hi, I understand how to swap depths of one movie clip with another, but what I need is to click on a movie clip and have that clip be sent to the back, or lowest level. Basically I will have four movieclips, what I want is to click on one clip and make that clip the background so the other three will play on top of it. I don’t want to have a whole mess of code, just something as simple as possible. Does anyone have any suggestions as to what the simplest way of doing this would be? Thank you.