Fifty knocked out of the squadron in battle (5)

I believe the answer is:

fight

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'battle' is the definition.
(I know that battle can be written as fight)

I don't understand the rest of the clue.

(Other definitions for fight that I've seen before include "Struggle; quarrel" , "Strive - struggle" , "Scrap" , "Campaign against - quarrel" , "Contest" .)

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

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