Boxers crack quickly. What a mess! (4,9)

I believe the answer is:

dogs breakfast

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'what a mess' is the definition.
(I've seen this before)

'boxers crack quickly' is the wordplay.
'boxers' becomes 'dogs' (I can't justify this - if you can you should give a lot more credence to this answer).
'crack' becomes 'break'.
'quickly' becomes 'fast' (synonyms).
'dogs'+'break'+'fast'='DOGS BREAKFAST'

Can you help me to learn more?

(Other definitions for dogs breakfast that I've seen before include "Mess - pet food" , "Darkest of bags (anag)" , "Hash?" , "Mess (food for Fido?)" , "Confused mess" .)

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

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