Eventually a number start to die, alas (7)

I believe the answer is:

someday

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

'eventually' is the definition.
(I've seen this before)

I don't understand how the remainder of the clue works.

(Other definitions for someday that I've seen before include "An unspecified time in the future" , "eventually" , "When will my prince come" , "song" , "At a future time; samoyed (anag.)" .)

I've seen this clue in the Sydney Morning Herald.

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.