Observe conclusion before last part of book (7)

'part of book' is the definition.
(I know that endnote is part of text)

'observe conclusion before' is the wordplay.
'observe' becomes 'note' (synonyms).
'conclusion' becomes 'end' (something's conclusion is its end).
'before' says to put letters next to each other.
'note' put after 'end' is 'ENDNOTE'.

'last' acts as a link.
I am not very happy about this link. It may be part of another bit of the clue.

Can you help me to learn more?