Odds are level on Sunday (5)
I believe the answer is:
evens
'odds' is the definition.
(I've seen this in other clues)
'are level on sunday' is the wordplay.
'are level' becomes 'even' (similar in meaning).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'sunday' becomes 's'.
'even'+'s'='EVENS'
(Other definitions for evens that I've seen before include "straight bet" , "Odds offering equal chance of win or lose" , "Balanced odds" , "Bookies' odds matching the amount staked" , "decreases" .)