A new corporation importing English alarm of prewar design (10)

I believe the answer is:

antebellum

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'a new corporation importing english alarm of prewar design' is the definition.
I can't tell whether this defines the answer.

'a new corporation importing english alarm of prewar design' is the wordplay.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'corporation' becomes 'tum' ('corporation' can humorously mean belly fat).
'importing' means one lot of letters goes inside another.
'english' becomes 'E' (abbreviation).
'alarm of prewar design' becomes 'bell' (I can't justify this - if you can you should believe this answer much more).
'e'+'bell'='ebell'
'tum' going around 'ebell' is 'tebellum'.
'a'+'n'+'tebellum'='ANTEBELLUM'

Can you help me to learn more?

(Another definition for antebellum that I've seen is " prior to hostilities".)

I've seen this clue in The Independent.

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