Mistake demolishing English house? (4)
I believe the answer is:
gaff
'house?' is the definition.
(gaff can informally mean someone's house)
'mistake demolishing english' is the wordplay.
'mistake' becomes 'gaffe' (a gaffe is a mistake or error).
'demolishing' is a deletion indicator.
'english' becomes 'e' (abbreviation).
'gaffe' with 'e' taken out is 'GAFF'.
(Other definitions for gaff that I've seen before include "Iron hook for landing big fish" , "Speaker's mistake" , "Landing hook - one's flat" , "Spar" , "House, once?" .)