Washington, DC time zone (3)

I believe the answer is:

est

(Other definitions for est that I've seen before include "Suffix showing superlative" , "psychological programme" , "self-improvement programme" , "Time Americans adopted" .)

I've seen this clue in The Star Tribune.

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.