Genuine floor woman added to first of rooms (6)
I believe the answer is:
kosher
'genuine' is the definition.
(I've seen this in another clue)
'floor woman added to first of rooms' is the wordplay.
'floor' becomes 'ko' (I've seen this in other clues).
'woman' becomes 'she'.
'added to' means one lot of letters go next to another.
'first of rooms' becomes 'r' (1st letter of 'rooms').
'ko'+'she'+'r'='KOSHER'
(Other definitions for kosher that I've seen before include "Of food, conforming to requirements of Jewish law" , "Legitimate (Jewish food)" , "(Of food) meeting Jewish dietary law" , "strict rules" , "over there OK?" .)