Naked old woman in apartment (8)
I believe the answer is:
flagrant
'naked' is the definition.
(thesaurus)
'old woman in apartment' is the wordplay.
'old woman' becomes 'gran' (short for grandmother).
'in' indicates putting letters inside.
'apartment' becomes 'flat' (synonyms).
'gran' put within 'flat' is 'FLAGRANT'.
(Other definitions for flagrant that I've seen before include "Very bad and obvious, say offence" , "Being shameless" , "Patent" , "Barefaced" , "Openly outrageous" .)