Nun’s outfit at home (7)
I believe the answer is:
'home' is the definition.
(I know that home can be written as habitat)
'nun's outfit at' is the wordplay.
'nun's outfit' becomes 'habit' (I am not sure about this - if you are sure you should believe this answer much more).
Can you help me to learn more?
(Other definitions for habitat that I've seen before include "Animal's environment" , "Local environment" , "Shop founded by Terence Conran" , "One's normal environment" , "Natural home of wildlife" .)