What's the chances of veterans eliminating rat? (5)

I believe the answer is:

evens

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

'what's the chances' is the definition.
(I've seen this before)

I don't understand the remainder of the clue.

(Other definitions for evens that I've seen before include "Half a chance" , "1-1" , "50-50 odds" , "Odds on something very likely to win" , "Smooths the odds" .)

I've seen this clue in the Irish Times and the Irish Times (Crosaire).

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.