Final chapter Poe composed with guile (8)
I believe the answer is:
epilogue
'final chapter' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe there's a link between them I don't understand?
'poe composed with guile' is the wordplay.
'composed with' indicates anagramming the letters.
'poe' anagrammed with 'guile' gives 'EPILOGUE'.
Can you help me to learn more?
(Other definitions for epilogue that I've seen before include "Postscript to a literary work" , "Late religious message" , "Final section (of play)" , "Short postscript" , "Final part of book" .)