How to separate and already established icloud account
I would like to provide a more complete answer.

First of all, you should create an Apple ID (iCloud account) for your daughter.

Once it's done, you can activate on your phone what Apple calls Family Sharing. This will make you the family owner. You can find it in your Settings app. Here is the documentation to set it up.

Once done, you just have to pair her account through her phone to yours.

This feature will allow you to share bought application or media and give you additional features such as location... But you will also be able to share the payment methods with control options ("need to ask for authorisation before buying anything"...).