Keynote article by the author (5)
I believe the answer is:
theme
'keynote' is the definition.
(thesaurus)
'article by the author' is the wordplay.
'article' becomes 'the' (the definite article in English).
'by' says to put letters next to each other.
'the author' becomes 'me' (the author of the crossword).
'the'+'me'='THEME'
(Other definitions for theme that I've seen before include "Burden" , "thing under discussion" , "Subject of a talk or piece of writing" , "essay" , "Subject (of talk, text, etc)" .)