what to do when your 8 year old daughter has an enlarged clitoris?

I’m not sure what you mean by enlarged, but clitorises come in many different sizes which is usually of no concern; however, this could be an indication of hormone imbalances. There are also many children who are born intersex whose primary sex characteristics allow them to appear biologically female. I suggest taking her to see a doctor. Explain your concerns (which do not seem to be extremely time sensitive, assuming that the enlargement has persisted for a while and isn’t causing her any discomfort) and the doctor can give you a definitive clinical answer.