Noteworthy occasion (3-6,3)

I believe the answer is:

red-letter day

(Other definitions for red-letter day that I've seen before include "Momentous date" , "Special occasion in calendar" , "Memorable occasion" , "Special date in the calendar" , "Memorably important occasion" .)

I've seen this clue in The Independent.

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.