’ouse introducing marginally better card game (5)
I believe the answer is:
ombre
'card game' is the definition.
(I know that Ombre is a card game)
''ouse introducing marginally better' is the wordplay.
''ouse' becomes ''ome' ('home' - homing is a kind of housing - said with the 'H' dropped, a cockney accent, like 'house' was).
'introducing' indicates putting letters inside (some letters introduced or inserted into others).
'marginally better' becomes 'br' (I can't explain this - if you can you should give a lot more credence to this answer).
'ome' going around 'br' is 'OMBRE'.
Can you help me to learn more?
(Other definitions for ombre that I've seen before include "Shaded" , "- Stravinsky, composer" , "Three-player card game" , "Card game, the name derived from the Spanish for man" , "Card-game for three; rob me (anag.)" .)