Subject of article written by yours truly (5)
I believe the answer is:
theme
'subject' is the definition.
(theme can mean a topic or subject)
'article written by yours truly' is the wordplay.
'article' becomes 'the' (the definite article in English).
'written by' means one lot of letters go next to another.
'yours truly' becomes 'me' (the person who set this crossword).
'the'+'me'='THEME'
'of' acts as a link.
(Other definitions for theme that I've seen before include "Topical item" , "He met (anag) - subject" , "Burden" , "argument" , "matter for discussion" .)