The most common and most likely answer to this crossword clue is the 6 letter word GABBLE
I've seen this crossword clue in The Daily Telegraph
G
A
B
B
L
E
More clues leading to the result GABBLE
Buddy explains!
The straight part
We know that "Chatter" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case chatter = gabble.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 GABBLE mean?
GABBLE noun- Confused or unintelligible speech.
- To talk fast, idly, foolishly, or without meaning.
- To utter inarticulate sounds with rapidity.