Hey Akiko, it's best to say, "I need more clarification.". This would be the more appropriate response.

Yeah! Thank yo David!

In this situation “clarity” is the correct choice.

Your sentence requires a noun, so ‘clarify’ isn’t a possibility. ‘clarity’ and ‘clarification’ are both possible but have different meanings. ‘clarity’ is the state of being clear. ‘clarification’ is the process of making something more clear. I need clarity. I need some (some) clarification. (There is something unclear that needs to be made clearer. This would be more common.)