Child, one accommodated in large shed (5)
I believe the answer is:
bairn
'child' is the definition.
(Scottish and northern English term for a child)
'one accommodated in large shed' is the wordplay.
'one' becomes 'i' (Roman numeral).
'accommodated in' is an insertion indicator.
'large shed' becomes 'barn' (I've seen this before).
'i' going into 'barn' is 'BAIRN'.
(Other definitions for bairn that I've seen before include "Northern child" , "A Scottish child?" , "Child in Scotland" , "A tot of Scotch" , "Kid" .)