Isaac's son devoured by songbird, detailed in book (9)
I believe the answer is:
thesaurus
'book' is the definition.
(thesaurus is a kind of book)
'isaac's son devoured by songbird detailed' is the wordplay.
'isaac's son' becomes 'Esau' (son of Isaac in the Bible).
'devoured by' means one lot of letters goes inside another.
'songbird' becomes 'thrush' (type of songbird).
'detailed' means to remove the last letter (the word must be end-less or 'de-tailed').
'thrush' with its last letter taken off is 'thrus'.
'esau' inserted within 'thrus' is 'THESAURUS'.
'in' acts as a link.
(Other definitions for thesaurus that I've seen before include "Wordbook" , "Wordy book" , "Volume of synonyms" , "Word-finder" , "Reference work" .)