Game of rugby to start late, as likely as not? (5)
I believe the answer is:
evens
'likely as not?' is the definition.
(I've seen this before)
'game of rugby to start late' is the wordplay.
'game of rugby' becomes 'sevens' (rugby with seven players on each team).
'to start late' means to remove the first letter (the word starts from its second letter).
'sevens' with its initial letter removed is 'EVENS'.
'as' is the link.
(Other definitions for evens that I've seen before include "50-50 chance" , "less likely than 27 [ODDS-ON]" , "square" , "Balanced odds" , "Kind of betting odds on seven" .)