Something you haven't been able to do on U.S. flights since 2000

SMOKE

Think of a habit once common in airplane cabins that was banned for health and safety reasons after a certain year. It’s often associated with a break area outside offices.

This clue refers to the ban on smoking on all U.S. commercial flights, which took full effect in 2000 after years of restrictions. The answer "SMOKE" directly names the action that was prohibited, making it a straightforward definition-style clue. There’s no wordplay here—it’s a simple reference to a well-known regulation in air travel. If you’ve flown in the U.S. since then, you’d know lighting up isn’t an option.