Enclosure surrounds extravagant country residence (7)
I believe the answer is:
cottage
'country residence' is the definition.
(I've seen this before)
'enclosure surrounds extravagant' is the wordplay.
'enclosure' becomes 'cage' (cage is a kind of enclosure**).
'surrounds' indicates putting letters inside.
'extravagant' becomes 'ott' (I've seen this in other clues).
'cage' enclosing 'ott' is 'COTTAGE'.
(Other definitions for cottage that I've seen before include "Small single-storey dwelling" , "Small house with a single storey" , "Cheese pie industries all may chase this" , "Rural dwelling" , "Rural house" .)