Paradoxically they could be evens (4)

I believe the answer is:

odds

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

'they could be evens' is the definition.
(I've seen this before)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for odds that I've seen before include "Estimate of likelihood" , "Variance" , "Chances of occurrence" , "Betting ratio" , "ten to one?" .)

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