The most common and most likely answer to this crossword clue is the 7 letter word CHATTER
I've seen this crossword clue in The Sunday Telegraph
C
H
A
T
T
E
R
More clues leading to the result CHATTER
- Clooney talk?
- Talk idly about her taking in a race
- Threat posed by introduction of Calor gas
- Idle talk about milliner
- Rabbit extracted from magic hat? Terrific!
- Talk about person said to be mad
- It goes on incessantly, even when idle
- Prattle about milliner
- Small talk primarily concerning manufacturer of headgear
- Gas milliner gets after drop of Coca-Cola
Buddy explains!

The straight part
We know that "Rabbit" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rabbit = chatter.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 CHATTER mean?
CHATTER noun- Talk, especially meaningless or unimportant talk.
- The sound of talking.
- The sound made by a magpie.
- An intermittent noise, as from vibration.
- In national security, the degree of communication between suspect groups and individuals, used to gauge the degree of expected terrorist activity.
- 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.
- One who chats
- A user of chat rooms