House could be this busy (8)
I believe the answer is:
occupied
I believe this is a double definition.
'house could be this' is the first definition.
'busy' is the second definition.
('occupied' can be similar in meaning to 'busy')
(Other definitions for occupied that I've seen before include "Inhabited, held" , "Lived in" , "In use or busy with something" , "Captured" , "as ladies often seem to be ..." .)