Article, so incomprehensible in parts (9)

I believe the answer is:

sectorial

'in parts' is the definition.
(divided into sectors)

'article so incomprehensible' is the wordplay.
'incomprehensible' indicates anagramming the letters (an incomprehensible jumbling of the letters).
'article'+'so'='articleso'
'articleso' is an anagram of 'SECTORIAL'.

(Another definition for sectorial that I've seen is " of an area".)

I've seen this clue in The Guardian.

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