Price of flat you raised after day (4,5)
I believe the answer is:
even money
'price' is the definition.
(type of bet)
'flat you raised after day' is the wordplay.
'flat' becomes 'even' (level).
'you' becomes 'ye' (historical version of 'you').
'raised' says the letters should be written backwards (going up in a down clue).
'after' says to put letters next to each other.
'day' becomes 'mon' (abbreviation for Monday).
'ye' written backwards gives 'ey'.
'ey' after 'mon' is 'money'.
'even'+'money'='EVEN-MONEY'
'of' is the link.
(Other definitions for even money that I've seen before include "likely to happen!" , "A good chance" , "Odds offering an equal chance of winning or losing" , "Betting odds offering chance to win the amount wagered" , "Kind of bet where you stand to win or lose the sum wagered" .)