Wordbook the governor’s brought into house (9)
I believe the answer is:
thesaurus
'wordbook' is the definition.
(thesaurus is a kind of wordbook)
'the governor's brought into house' is the wordplay.
'the governor's' becomes 'HEs' (abbreviation for His or Her Excellency).
'brought into' means one lot of letters goes inside another.
'house' becomes 'taurus' (Taurus is an example).
'hes' inserted inside 'taurus' is 'THESAURUS'.
(Other definitions for thesaurus that I've seen before include "Word-finder" , "Wordbook" , "Wordy book" , "Reference book" , "Book of words with synonyms, antonyms etc" .)