Wordy tome His Eminence has taken into house (9)
I believe the answer is:
thesaurus
'wordy tome his' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'eminence has taken into house' is the wordplay.
'eminence has' becomes 'hes' (I can't justify this - if you can you should believe this answer much more).
'taken into' means one lot of letters goes inside another.
'house' becomes 'Taurus' (Taurus is an example).
'hes' placed inside 'taurus' is 'THESAURUS'.
Can you help me to learn more?
(Other definitions for thesaurus that I've seen before include "Reference work" , "Word book" , "Dictionary" , "Reference book" , "Book of words with synonyms, antonyms etc" .)