Skill workers put into fitting set of rooms (9)
I believe the answer is:
apartment
'set of rooms' is the definition.
(I've seen this before)
'skill workers put into fitting' is the wordplay.
'skill' becomes 'art' (both can mean a talent).
'workers' becomes 'men' (men can mean staff or employees).
'put into' means one lot of letters goes inside another.
'fitting' becomes 'apt' (I've seen this in another clue).
'art'+'men'='artmen'
'artmen' put within 'apt' is 'APARTMENT'.
(Other definitions for apartment that I've seen before include "Penthouse" , "place to live" , "pad" , "quarters" , "Set of rooms or American flat" .)