Plain article brought into house (7)
I believe the answer is:
vanilla
'plain' is the definition.
(I've seen this in another clue)
'article brought into house' is the wordplay.
'article' becomes 'an' (English indefinite article).
'brought into' means one lot of letters goes inside another.
'house' becomes 'villa' (villa is a kind of house).
'an' put inside 'villa' is 'VANILLA'.
(Other definitions for vanilla that I've seen before include "lacking any special features" , "Popular ice cream flavour" , "Flavour got from pods" , "Common flavour for ices" , "Nice flavouring for ice-cream" .)