EventListener inside External MovieClip

How do I listen for an event in an external movieclip?

var DRALoader:Loader = new Loader();
var Phone:URLRequest = new URLRequest(“DRA_Phone.swf”);

DRALoader.load(Phone);

I can run a function located in the loadedl movieclip:
(DRALoader.content as MovieClip).closeClip();

But I can’t seem to target a button onClick event stored inside the loaded MovieClip.