Ordinary article kept in large house (7)
I believe the answer is:
vanilla
'ordinary' is the definition.
(vanilla can mean ordinary or conventional)
'article kept in large house' is the wordplay.
'article' becomes 'an' (English indefinite article).
'kept in' indicates putting letters inside.
'large house' becomes 'villa' (I've seen this before).
'an' going within 'villa' is 'VANILLA'.
(Other definitions for vanilla that I've seen before include "Flavouring from pod of certain orchids" , "Common flavour for ices" , "Popular ice-cream, flavour" , "Flavouring derived from an orchid" , "Nice flavouring for ice-cream" .)