The Middle East initially is the subject (5)
I believe the answer is:
theme
'the subject' is the definition.
(theme can mean a topic or subject)
'the middle east initially' is the wordplay.
'initially' says to take the initial letters.
The initial letters of 'middle east' is 'me'.
'the'+'me'='THEME'
'is' is the link.
(Other definitions for theme that I've seen before include "Topic, leitmotif" , "subject,motif" , "[(type of) PARK]" , "Musical idea; topic" , "Main idea or topic" .)