1. I must have done something to offend Louise—she’s been so unfriendly to me. I told her I wanted to clear the air, but she just turned and walked away from me.
2. The boss called a meeting because there were lots of rumors flying around the office. He said he wanted to clear the air.

Synonym: bury the hatchet. The expression originates from the idea that when there is smoke or fog in the air, it is difficult to see.