Clear like space means only reflect action. Zen means correct conditional reflection. It means you respond to each situation correctly, meticulously. It means to understand your correct job in this moment. Correct kong-an practice means great question plus great faith and great courage.
Great question means no intellectual-style thinking.
So one question means only don't know. No thinking at all. Just do it. That's correct kong-an practice. But if you are attached to a kong-an or this style of practicing, then you have a big problem.