A room with old academic is a battle (10)

I believe the answer is:

armageddon

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'battle' is the definition.
(I know that Armageddon is a type of battle)

'a room with old academic' is the wordplay.
'room with' becomes 'rm' (I've seen this in other clues. I am not sure about the 'with' bit.).
'old' becomes 'aged' (similar in meaning).
'academic' becomes 'don' (type of academic - especially at Oxbridge).
'a'+'rm'+'aged'+'don'='ARMAGEDDON'

'is a' is the link.

Can you help me to learn more?

(Other definitions for armageddon that I've seen before include "Catastrophic conflict" , "extremely destructive conflict" , "Terrible war" , "terminal struggle" , "final engagement" .)

I've seen this clue in The Telegraph.

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