In which troops eat shambles? (4)

I believe the answer is:

mess

I'm a little stuck... Click here to teach me more about this clue!

'shambles?' is the definition.
(I've seen this before)

I don't understand the remainder of the clue.

(Other definitions for mess that I've seen before include "Confused situation" , "Where soldiers may eat" , "Disagreeable mixture" , "Where those who serve eat" , "Where men might eat" .)

I've seen this clue in the Sydney Morning Herald.

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