Arms of the fighting services (7,2,3)

I believe the answer is:

weapons of war

'arms of the fighting services' is the definition.
(arms as in weapons)

'arms of the fighting' is the wordplay.
'arms' becomes 'weapons' ('weapon' can be a synonym of 'arm').
'the fighting' becomes 'war'.
'weapons'+'of'+'war'='WEAPONS OF WAR'

I've seen this clue in The Globe and Mail.

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