It is always good to ask some clarifying questions at the end of the interview. I would say, it is even necessarily sometimes, otherwise you may misunderstand or miss something.
Actually, clarifying questions are divided into 3 types:
1. Questions that clarify the objective of the case interview
2. Questions that help you understand more about the company and its objectives
3. Questions clarifying some terms that you are unfamiliar with
It is likely, that you don't have specialized knowledge at ther start and it is quite ok to ask the interviewer for the definition.