A role people took, originally flat (9)
I believe the answer is:
apartment
'originally flat' is the definition.
'apartment' can be an answer for 'flat' (I've seen this before). I'm unsure of the 'originally' bit.
'a role people took' is the wordplay.
'role' becomes 'part' (eg a part or role in a film).
'people' becomes 'men' (men are people).
'took' becomes 't' (this could be a standard abbreviation I've not previously seen).
'a'+'part'+'men'+'t'='APARTMENT'
Can you help me to learn more?
(Other definitions for apartment that I've seen before include "Flat (mainly US)" , "pad" , "Set of rooms or American flat" , "quarters" , "19 across" .)