Found in Poirot it lends book name (5)
I believe the answer is:
title
'book name' is the definition.
(I've seen this in another clue)
'found in poirot it lends' is the wordplay.
'found in' indicates a hidden word.
'TITLE' is hidden within 'poirot it lends'.
(Other definitions for title that I've seen before include "Right - name - rank" , "Right - name - address" , "inscription" , "Name; heading" , "Name, honorific" .)