Complete house enveloped in depression (8)
I believe the answer is:
thorough
'complete' is the definition.
('thorough' can be similar in meaning to 'complete')
'house enveloped in depression' is the wordplay.
'house' becomes 'ho' (abbreviation for house).
'enveloped in' means one lot of letters goes inside another.
'depression' becomes 'trough' (trough is a kind of depression**).
'ho' placed within 'trough' is 'THOROUGH'.
(Other definitions for thorough that I've seen before include "Complete - painstaking - unqualified" , "Painstaking; absolute" , "Meticulous - exhaustive" , "Assiduous, painstaking" , "Out-and-out, utter" .)