Long stop in expensive houses (4)
I believe the answer is:
pine
'long' is the definition.
('pine' can be a synonym of 'long')
'stop in expensive houses' is the wordplay.
'houses' says the answer is hidden in the clue (part of the clue houses the answer).
'PINE' is hidden in the letters of 'stop in expensive'.
(Other definitions for pine that I've seen before include "Kind of needle" , "Scots fir" , "type of wood" , "Mope; tree" , "Long - tree" .)