Where service people eat dog's dinner? (4)

I believe the answer is:

mess

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'dog's dinner?' is the definition.
(I've seen this before)

I can't explain the rest of the clue.

(Other definitions for mess that I've seen before include "State of confusion - where servicemen eat" , "Military dining room" , "Army canteen - shambles" , "Where sailors eat" , "Disagreeable mixture" .)

I've seen this clue in The Times.

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