Crossword Genius

Communist allowed ground-up dry tea for celebration (3,6,3)

Ross

I believe the answer is:

red letter day

I'm a little stuck... Click here to teach me more about this clue!

(Other definitions for red letter day that I've seen before include "memorable time" , "Important occasion" , "Memorable event" .)

I've seen this clue in The Telegraph.
Want a hint initially instead of a full solution? Install my app