Chance in card game initially blown (5)
I believe the answer is:
Here is my best explanation:
'chance' is the definition.
(I've seen this before)
'card game initially blown' is the wordplay.
'card game' becomes 'sevens' (sevens is a kind of card game).
'initially blown' means to remove the first letter.
'sevens' with its first letter removed is 'EVENS'.
'in' acts as a link.
(Other definitions for evens that I've seen before include "decreases", "Half a chance", "Odds of 50-50", "Odds offering equal chance of win or lose", "Likelihood", "Quits", "Smooths the odds", "Kind of betting odds on seven", "Oddly, these could be odds" and "Equal stakes on both sides in bet".)