This territory is party central (6)
I believe the answer is:
domain
'this territory' is the definition.
(I've seen this before)
'party central' is the wordplay.
'party' becomes 'do' (do is a kind of party).
'central' becomes 'main' (I've seen this in another clue).
'do'+'main'='DOMAIN'
'is' acts as a link.
(Other definitions for domain that I've seen before include "Scope of knowledge - owned land" , "Sphere or territory" , "Special region, area of expertise" , "Territory over which someone reigns" , "A district sphere of influence" .)