Try rephrasing your question to the truth. For example don't you mean "My FATHER insists I dress in girly clothes, even when I don't want to and he won't listen to me. What should I do?
But the answer is the same for both questions. Consider WHY it is important to him.
If you are in fact his wife, which I doubt, it's like any other conflict in marriage. You discuss the issue and work to resolve it, or you make a compromise. If you are the child, as I believe you are, you do what your Dad says until you are no longer a child and ready to take responsibility for yourself moving out on your own.