Pound secures extravagant type of cheese (7)
I believe the answer is:
cottage
'type of cheese' is the definition.
(as in cottage cheese)
'pound secures extravagant' is the wordplay.
'pound' becomes 'cage' (both can mean an enclosure for animals).
'secures' indicates putting letters inside.
'extravagant' becomes 'OTT' (short for over the top).
'cage' enclosing 'ott' is 'COTTAGE'.
(Other definitions for cottage that I've seen before include "building" , "simple accommodation" , "Rural dwelling" , "Rural house" , "Small home" .)