Betting odds, numbers originally cut (5)
I believe the answer is:
evens
'betting odds' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for evens that I've seen before include "50-50 chance" , "Level betting" , "Levels - odds" , "Bookies' odds matching the amount staked" , "Quits" .)