The most common and most likely answer to this crossword clue is the 7 letter word YAPPING
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Buddy explains!

The straight part
We know that "Typical behaviour of boxer, for instance" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case typical behaviour of boxer, for instance = yapping.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.
What does YAPPING mean?
YAPPING verb- Of a small dog, to bark.
- To talk, especially excessively; to chatter.
- To rob or steal from (someone).
- A sound that yaps.