The most common and most likely answer to this crossword clue is the 10 letter word CHATTERING
I've seen this crossword clue in The Daily Telegraph
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More clues leading to the result CHATTERING
- Milliner: not ‘dealer in candle-making’ – that’s silly talk!
- Mad person in custody is not going to start casual conversation
- Mad character in following chapter originally goes rabbiting
- Caught mad character in government, babbling
- Chewing the fat, the cat’s upset by call
- Milliner: not 'dealer in candle-making' – that's silly talk!
- Having a rabbit making animal noises
Buddy explains!

The straight part
We know that "rabbiting" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rabbiting = chattering.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 CHATTERING mean?
CHATTERING verb- To talk idly.
- Of teeth, machinery, etc, to make a noise by rapid collisions.
- To utter sounds which somewhat resemble language, but are inarticulate and indistinct.
- A noise that chatters.
- Output fluctuation before reaching a stable condition.