Minds one's P's and Q's

BEHAVES

Acts politely or follows proper etiquette, especially in social situations where good manners are expected.

The phrase "minds one's P's and Q's" is an old English saying meaning to be careful about manners or behavior. The clue plays on this idiom, where "minding" your P's and Q's essentially means acting properly—hence the answer "BEHAVES." It’s a straightforward definition with no hidden wordplay, just a nod to the expression’s literal meaning of conducting oneself well.