Level small chances (5)
I believe the answer is:
evens
'chances' is the definition.
(I've seen this before)
'level small' is the wordplay.
'level' becomes 'even' (similar in meaning).
'small' becomes 's' (abbreviation - e.g. clothes size).
'even'+'s'='EVENS'
(Other definitions for evens that I've seen before include "Bookies' odds matching the amount staked" , "decreases" , "Likelihood" , "These are odds, strangely" , "square" .)