1) Don't evade the question, but if you're really not sure what it means, don't try to answer it, but restate it to make sure you're answering the question, i.e. "If I'm understanding your honor's question correctly, you mean X?" They say yes - answer; they say something else - answer that question.
Comments
3) On the same note, if you're winning, don't feel compelled to go through your whole outline or use all your time.
A mentor in my first year in practice told me that you need to know two things - First, whether you win or lose is not a reflection on your ability as a lawyer. Second, and more importantly, your ability as a lawyer doesn't define you as a person.