Cryptic crossword clue
Bet it gets cold in the water, so be nonchalant 4,2,4

The most common and most likely answer to this crossword clue is the 4 plus 2 plus 4 letter word PLAY IT COOL

I've seen this crossword clue in Financial Times
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Buddy explains!

The straight part
We know that "be nonchalant" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case be nonchalant = play it cool.
The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.
This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.

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