Essence of Eastern book about Greek character (7)
I believe the answer is:
epitome
'essence' is the definition.
(I've seen this before)
'eastern book about greek character' is the wordplay.
'eastern' becomes 'e'.
'book' becomes 'tome' (tome is a kind of book**).
'about' says to put letters next to each other.
'greek character' becomes 'pi' (letter from the Greek alphabet).
'tome' put after 'pi' is 'pitome'.
'e'+'pitome'='EPITOME'
'of' is the link.
(Other definitions for epitome that I've seen before include "Typical example, prototype" , "Essence or embodiment" , "Archetype, typical example" , "Exemplar - embodiment" , "Paradigm" .)