Cheat demolished a posh French house (7)
I believe the answer is:
chateau
'french house' is the definition.
'chateau' can be an answer for 'house' (chateau is a kind of house). I am not sure about the 'french' bit.
'cheat demolished a posh' is the wordplay.
'demolished' is an anagram indicator.
'posh' becomes 'u' (abbreviation for upper-class - opposite to non-U).
'cheat' with letters rearranged gives 'chate'.
'chate'+'a'+'u'='CHATEAU'
Can you help me to learn more?
(Other definitions for chateau that I've seen before include "Castle (1)" , "Impressive dwelling in France" , "French stately home" , "eg Margaux" , "Manor-house in France" .)