Casualties, one of which may be termed dead (6)

I believe the answer is:

losses

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'casualties' is the definition.
(loss is a kind of casualty)

I don't understand how the remainder of the clue works.

(Other definitions for losses that I've seen before include "They're not profits" , "Amounts by which the costs of a business exceed its revenue" .)

I've seen this clue in the Evening Standard.

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