As far as admissions goes, "clinical experience" pretty much encompasses anything where you'll be interacting on a personal level with patients. The admissions committee wants to know that you've experienced the good side, and the bad side, of interacting with people. It's one thing to talk to people when lining up at the grocery checkout, but an entirely different animal when the person is in pain, or has just received terrible news. Having this patient contact is crucial to seeing whether you have the empathy, and sensitivity for being a good physician.
What most premeds usually do is volunteer at the local hospital, often in the Emergency department. There, you'll get to greet, and often converse with the patient and his/her family in the waiting room, which helps develop your people skills. Candystriping is another option. Volunteering at a local clinic is acceptable as well.
Another avenue to gaining clinical experience comes from "shadowing" a physician for a day. Here, by following and observing a doctor, you'll gain an understanding of the doctor/patient relationship, but from the *doctor's* perspective. Again, this will give you some insight as to what a career in medicine will encompass.