Phone reminder, e.g (5)

I believe the answer is:

alert

(Other definitions for alert that I've seen before include "Put on guard, warn" , "On one's toes" , "Watchful, sharp" , "Quick to notice" , "Lively" .)

I've seen this clue in the USA Today.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.