Given assurance, from public library order in a book (6)
I believe the answer is:
aplomb
'given assurance' is the definition.
'aplomb' can be an answer for 'assurance' (I've seen this before). I'm unsure of the 'given' bit.
'public library order in a book' is the wordplay.
'public library' becomes 'PL' (abbreviation for public library).
'order' becomes 'om' (Order of Merit).
'in' indicates putting letters inside.
'book' becomes 'b' (abbreviation for book).
'pl'+'om'='plom'
'a'+'b'='ab'
'plom' placed into 'ab' is 'APLOMB'.
'from' acts as a link.
Can you help me to learn more?
(Other definitions for aplomb that I've seen before include "Self-possession, assurance" , "Self-satisfied dignity and confidence" , "'Poise, sang-froid (6)'" , "Nonchalant confidence" , "Great coolness and composure under strain" .)