The most common and most likely answer to this crossword clue is the 3 plus 3 plus 4 plus 2 plus 2 letter word FOR THE HELL OF IT
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More clues leading to the result FOR THE HELL OF IT
Buddy explains!

The straight part
We know that "just because you can" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case just because you can = for the hell of it.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.