It's not getting any better for idlers from World Series (5)

I believe the answer is:

worse

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

'series' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.

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

Can you help me to learn more?

(Other definitions for worse that I've seen before include "Inferior to another" , "Less good" , "more unpleasant" , "More serious" , "Of poorer quality" .)

I've seen this clue in the Irish 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.