Examples one's seen in record books (8)
I believe the answer is:
epitomes
'examples' is the definition.
(I know this)
'one's seen in record books' is the wordplay.
'one' becomes 'i' (Roman numeral).
'seen in' is an insertion indicator.
'record' becomes 'EP' (abbreviation for extended play record).
'books' becomes 'tomes' (tome is a kind of book).
'ep'+'tomes'='eptomes'
'i' inserted within 'eptomes' is 'EPITOMES'.
(Other definitions for epitomes that I've seen before include "Perfect examples" , "Standards or typical examples" .)