Everyone in the main is disorganised (3,2,3)

I believe the answer is:

all at sea

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'disorganised' is the definition.
I don't know anything about this answer so I can't tell whether this works.

'everyone in the main' is the wordplay.
'everyone' becomes 'all' (all people).
'in the main' becomes 'atsea' (I've seen this before).
'all'+'atsea'='ALL AT SEA'

'is' is the link.

Can you help me to learn more?

(Other definitions for all at sea that I've seen before include "Entire fleet's" , "state of confusion" , "Nobody in the dock" , "Completely confused on voyage?" , "Quite confused on the briny?" .)

I've seen this clue in The Independent.

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