Record one is in book to illustrate (9)
I believe the answer is:
epitomise
'to illustrate' is the definition.
('illustrate'->'epitomize' is in my internal thesaurus and 'ize'->'ise')
'record one is in' is the wordplay.
'record one' becomes 'epitome' (I can't explain this - if you can you should believe this answer much more).
'in' is an insertion indicator.
'epitome' enclosing 'is' is 'EPITOMISE'.
'book' acts as a link.
This may not be correct. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for epitomise that I've seen before include "Abstract" , "Embody perfectly a stated idea" , "to be a perfect example" , "Embody perfectly a stated quality" , "in a summary case" .)