Food fight? This contains some of the ammunition (8)

I believe the answer is:

lunchbox

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'contains some of the ammunition' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.

'food fight?' is the wordplay.
'food' becomes 'lunch' (lunch is a kind of food).
'fight?' becomes 'box' (boxing is a kind of fighting).
'lunch'+'box'='LUNCHBOX'

'this' acts as a link.

Can you help me to learn more?

(Another definition for lunchbox that I've seen is " tackle".)

I've seen this clue in The Irish Times.

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