The most common and most likely answer to this crossword clue is the 9 letter word LINGERING
I've seen this crossword clue in The Times
L
I
N
G
E
R
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Buddy explains!

The straight part
We know that "Hanging about" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case hanging about = lingering.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 LINGERING mean?
LINGERING verb- To stay or remain in a place or situation, especially as if unwilling to depart or not easily able to do so; to loiter.
- To remain alive or existent although still proceeding toward death or extinction; to die gradually.
- (often followed by on) To consider or contemplate for a period of time; to engage in analytic thinking or discussion.
- An act of lingering or waiting.
- That which lingers; a remnant.