Part of a building for accommodating the old (5)
I believe the answer is:
foyer
'part of a building' is the definition.
(I know that foyer is part of building)
'for accommodating the old' is the wordplay.
'accommodating' indicates putting letters inside.
'the old' becomes 'ye' (resembles a historical spelling of 'the').
'for' placed around 'ye' is 'FOYER'.
(Other definitions for foyer that I've seen before include "Reception lobby" , "Reception room or waiting area" , "Large entrance area" , "Theatrical" , "Theatre public area" .)