In principle there is no difference to a candidate-led case, and no need to overcomplicate things - just think logically and practically what makes sense to do. Finally it should resemble a real-life interaction, so just behave and do as you would do in any reasonable business conversation. Also the interview is not a one-way street and you can clarify whenever required. In case of doubts, just clarify with your interviewer - don't assume anything implicitly about the interviewer's question and the client goals to achieve.
The general rule is:
- Clarify and double-check the objective
- Ask clarifying and eliminating questions (and communicate them properly)
- Prepare and present your framework (and communicate it properly)
If the interviewer immediately asks a specific question and you have still something to clarify, ask if it's ok to still clarify something before answering his question.
If the interviewer gives you the case outline without a specific question and he doesn't seem to ask a question in the next few seconds, then just ask and clarify if you should think about a general structure to approach this issue.
Hope that helps - if so, please be so kind to give it a thumbs-up with the green upvote button below!