Summary of largely impressive book (7)
I believe the answer is:
epitome
'summary' is the definition.
(epitome is a kind of summary)
'largely impressive book' is the wordplay.
'largely' means to remove the last letter.
'impressive' becomes 'epic' (I've seen this before).
'book' becomes 'tome' (a tome is a book).
'epic' with its last letter removed is 'epi'.
'epi'+'tome'='EPITOME'
'of' is the link.
(Other definitions for epitome that I've seen before include "Paradigm" , "Essence or embodiment" , "Embodiment, type" , "Something embodying perfectly a stated quality or idea" , "Ideal example" .)