Crossword Genius

Muse having to leave for day (3)

Ross

I believe the answer is:

era

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

'for day' is the definition.
(day can mean an era of time)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for era that I've seen before include "Specific time" , "Important date" , "Important historical period" , "Eon" , "Are involved in time span" .)

I've seen this clue in The Times.
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.