Old empire church book (7)
I believe the answer is:
romance
'old empire' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'church book' is the wordplay.
'church' becomes 'Roman Church' (Roman Church is an example).
'book' becomes 'ce' (I can't justify this - if you can you should give a lot more credence to this answer).
'roman'+'ce'='ROMANCE'
Can you help me to learn more?
(Other definitions for romance that I've seen before include "Various languages such as French" , "Love-story" , "mysterious quality" , "Novel - love story" , "Make up stories - Menorca (anag)" .)