Unsuitable home — apartment (5)
I believe the answer is:
inapt
'unsuitable' is the definition.
(I've seen this before)
'home apartment' is the wordplay.
'home' becomes 'in' (to be in is to be (at) home).
'apartment' becomes 'apt' (abbreviation in property ads for example).
'in'+'apt'='INAPT'
(Other definitions for inapt that I've seen before include "Out of place" , "Not suitable or appropriate" , "not fit for purpose" , "It's clumsy" , "Ill-chosen, not suitable" .)