Queen admitting age retired to women's quarters (5)
I believe the answer is:
harem
'women's quarters' is the definition.
(historically, women's quarters in Muslim household)
'queen admitting age retired' is the wordplay.
'queen' becomes 'hm' (short for Her Majesty).
'admitting' means one lot of letters goes inside another (admit can mean to welcome in or accept).
'age' becomes 'era' (both can mean a long time).
'retired' shows that the letters should be reversed in order.
'era' backwards is 'are'.
'hm' going around 'are' is 'HAREM'.
'to' acts as a link.
(Other definitions for harem that I've seen before include "Set of wives" , "Collection of wives, concubines and female servants" , "a number of wives" , "Home to concubines" , "Concubines living together" .)