Children need to have some choices about what they eat. I think that blindly giving commands to "clean your plate" doesn't teach children to know when they're hungry and when they are full. It doesn't teach them how to make proper food choices when they are away from your table. Given the alarming rise in both obesity and eating disorders in children in this country, I think it's important to give a child some element of control over her food intake.
My advice is to prepare healthful meals that you approve of, and always try to include one dish (whether the main course or a side dish) that you know your daughter likes. Serve smaller portions of the things she doesn't like, and require that she taste everything. In this way, she will learn to keep trying new things even if she "knows" she doesn't like it. Kids' tastes do change, and something that she dislikes now may become appealing to her in the near future. After tasting everything, if she does not want to eat the new foods, don't force her. I think it's reasonable to have a couple of agreed-upon standby items available in the house that anyone who doesn't like the meal can eat instead: Yogurt, bagels, fruit, and raw veggies (carrots and cucumbers, for example) are all good choices.