Letters for a sellout

SRO

Think of what you’d see on a ticket when every seat in the house is taken.

"Letters for a sellout" plays on the idea of a sold-out event, where all tickets are gone. "SRO" stands for "standing room only," a term used when venues are so packed that only standing spots remain. The clue twists "sellout" to hint at the abbreviation rather than the literal meaning of betrayal, making it a clever misdirection. It’s a short, punny way to clue a common crossword abbreviation.