expression, godan verb (-ru)
have a drink; have a few drinks
Casual expression for drinking alcohol, often implying a relaxed or social setting. The amount is not strictly one cup; it can mean a few drinks.
仕事の後で一杯やらない？
How about having a drink after work?
彼は毎晩一杯やるのが習慣だ。
He has a habit of having a few drinks every night.