One living in villa without additions (7)
I believe the answer is:
vanilla
'without additions' is the definition.
(I've seen this before)
'one living in villa' is the wordplay.
'one' becomes 'an' (an apple is one apple).
'living in' indicates putting letters inside.
'an' put inside 'villa' is 'VANILLA'.
(Other definitions for vanilla that I've seen before include "conventional" , "Pod used in cookery" , "Ordinary" , "plant" , "Basic ice-cream" .)