To sum up, most of epic is boring to me (9)
I believe the answer is:
epitomise
'to sum up' is the definition.
('sum up'->'epitomize' is in my internal thesaurus and 'ize'->'ise')
'most of epic is boring to me' is the wordplay.
'most of' means to remove the last letter.
'boring' indicates putting letters inside (some letters must 'bore' a hole into other letters).
'epic' with its final letter removed is 'epi'.
'to'+'me'='tome'
'is' placed within 'tome' is 'tomise'.
'epi'+'tomise'='EPITOMISE'
(Other definitions for epitomise that I've seen before include "Abstract" , "Typify (S, not Z)" , "in a summary case" , "to be a perfect example" , "Embody perfectly a stated idea" .)