Watchdog's warning

GRR

Think of the sound a small but fierce guard dog might make when sensing an intruder—it’s short, guttural, and often repeated. This three-letter growl starts with a hard "G."

A watchdog is a dog that guards property, and its warning sound is often a low, threatening growl. The answer "GRR" mimics that growl in a simple, onomatopoeic way—just like you’d see in comics or cartoons. It’s a short, punchy representation of the noise, making it a perfect fit for a concise crossword answer. The clue plays on the literal sound rather than the word itself.