Subject of article on Middle East (5)
I believe the answer is:
theme
'subject' is the definition.
(theme can mean a topic or subject)
'article on middle east' is the wordplay.
'article' becomes 'the' (the definite article in English).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'middle east' becomes 'me' (abbreviation for Middle East).
'the'+'me'='THEME'
'of' is the link.
(Other definitions for theme that I've seen before include "matter for discussion" , "Subject of a talk or piece of writing" , "Subject (on which person writes, speaks)" , "idea of the work" , "tune used in Enigma Variations?" .)