Every expert once had questions they were embarrassed to ask.

Everyone who now looks authoritative spent time not understanding the basics, and most of them remember a question they were too self-conscious to ask. The difference between them and the people still stuck is usually just that they asked it eventually, often later than they should have.

Whatever basic thing you have never quite understood, ask about it now rather than after another year of working around it. Frame it plainly. You will find that expertise is far more porous than it appears from outside, and that the question was smaller than the avoidance had made it.