Their guns are out of order - you can bet on it (4,5)

I believe the answer is:

sure thing

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'order you can bet on it' is the definition.
I can't judge whether this defines the answer.

'their guns are out' is the wordplay.
'are out' is an anagram indicator (out can mean wrong or inaccurate).
'their'+'guns'='theirguns'
'theirguns' is an anagram of 'SURE THING'.

'of' is the link.

Can you help me to learn more?

(Other definitions for sure thing that I've seen before include "cert" , "of course" , "A certainty - I agree!" , "no chance of losing" .)

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

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