Poor arrangement in box is shared (9)
I believe the answer is:
corporate
'shared' is the definition.
Both the definition and answer are adjectives. Perhaps they are linked in a way I don't understand?
'poor arrangement in box' is the wordplay.
'arrangement' indicates an anagram.
'in' is an insertion indicator.
'box' becomes 'crate' (crate is a kind of box).
'poor' is an anagram of 'orpo'.
'orpo' inserted within 'crate' is 'CORPORATE'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for corporate that I've seen before include "Joint" , "Of a legal entity acting as an individual" , "Relating to a large group; united" , "belonging to a large company" , "Relating to a large group or company" .)