"R" in a car

REVERSE

Think of the gear that lets you back up when you're driving.

The clue plays on the letter "R" as part of the word "reverse," which is a gear in a car. Here, "R" isn’t just a standalone letter but the first letter of the answer, hinting at the car’s reverse function. It’s a simple abbreviation-style clue where the letter directly ties to the word’s meaning in driving.