Keynote article made less commercial (5)
I believe the answer is:
theme
'keynote' is the definition.
(thesaurus)
'article made less commercial' is the wordplay.
'article' becomes 'the' (the definite article in English).
'less' indicates named letters should be taken away.
'commercial' becomes 'ad' (abbreviation for advertisement).
'made' with 'ad' taken out is 'me'.
'the'+'me'='THEME'
(Other definitions for theme that I've seen before include "Subject matter, motif" , "Recurrent unifying idea" , "Signature tune" , "Musical motif" , "Leitmotiv" .)