About to go wrong initially over gaming house (6)
I believe the answer is:
casino
'gaming house' is the definition.
(casino is a kind of gaming house)
'about to go wrong initially over' is the wordplay.
'about' becomes 'ca' (abbreviation for 'circa').
'to go wrong' becomes 'sin' (to sin is to do wrong).
'initially' says to take the initial letters.
The first letter of 'over' is 'o'.
'ca'+'sin'+'o'='CASINO'
(Other definitions for casino that I've seen before include "Gambling establishment" , "Gambling place" , "Gambling emporium" , "Gambling-club" , "used by gamblers" .)