Courtyard - work to surround it with area that’s elevated (5)
I believe the answer is:
patio
'courtyard' is the definition.
(a patio is an outdoor space or courtyard)
'work to surround it with area that's elevated' is the wordplay.
'work' becomes 'op' (common abbreviation for 'opus').
'to surround' indicates putting letters inside.
'with' means one lot of letters go next to another.
'area' becomes 'a' (maths abbreviation).
'that's elevated' says the letters should be written backwards (in a down clue, letters go up).
'it'+'a'='ita'
'op' placed around 'ita' is 'oitap'.
'oitap' back-to-front is 'PATIO'.
(Other definitions for patio that I've seen before include "Place to sit" , "Paved eating area adjoining house" , "Spanish court" , "Exterior paved area" , "inner court" .)