Quietly copy conclusion of her essay (5)
I believe the answer is:
paper
'essay' is the definition.
(paper is a kind of essay)
'quietly copy conclusion of her' is the wordplay.
'quietly' becomes 'p' (p for piano and quiet).
'copy' becomes 'ape' (ape can mean to copy or imitate).
'conclusion of' suggests the final letters.
The last letter of 'her' is 'r'.
'p'+'ape'+'r'='PAPER'
(Other definitions for paper that I've seen before include "Treatise" , "First wedding anniversary" , "daily read?" , "Daily publication" , "Journal" .)