How to clarify questions to professors without seeming condescending?

Fellow student and TA here. But I am pretty sure that question is not academia-only.

To address your real question:

How do I interrupt them to clarify my doubt, without looking condescending and insulting?

In academia it is OK to interrupt speaker if they are way off-topic. It will save everyone's time. Something like

Oh, excuse me, I think you misunderstood. I am asking about X and Y, not about W and Q.

However, I would like to address this quote:

When I ask a question about something that is unusual in the technical sense , many times the professors do not understand my query properly, leading them to not answer my question

I emphasized "many times" to suggest that problem is on your side, not professors'. You should make sure that you understand the question yourself and made some effort answering it. Professors were teaching their subject, and thinking about it, for many years, so it is unlikely that your question is something ground-breaking while still relevant to the field. (you should post your sample unanswered Q here)

You should also ask question showing work:

Hey, teach. I am wondering how does one X with the Z? I was googling last night and closest thing I found is that you first Y and then W. I found it in the textbook by Dr. Firstname Middlename, but I can't grasp connection of X and Y. Can you help me out?

That also puts your question into broader context, which can help professor with answering.

Next, you should mention communication language. Are you both native speakers of the same languages? In academia, and STEM especially, that is not a valid assumption. You can solve that problem by writing email and ask prof to reply in written language as well.