Note carrying article on the subject (5)
I believe the answer is:
theme
'the subject' is the definition.
(synonyms)
'note carrying article' is the wordplay.
'note' becomes 'me' (musical note as in do-re-me).
'carrying' means one lot of letters go next to another (in a down clue, the bottom letters carry others).
'article' becomes 'the' (the definite article in English).
'me' after 'the' is 'THEME'.
'on' is the link.
(Other definitions for theme that I've seen before include "Subject (on which person writes, speaks)" , "Topic, leitmotif" , "Subject matter, topic" , "Thread, melody" , "Recurring melody" .)