The most common and most likely answer to this crossword clue is the 6 letter word GASBAG
I've seen this crossword clue in Financial Times
G
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More clues leading to the result GASBAG
- Rabbit lover to give back trap
- This person talks a long time: flipping endlessly
- One going on / whoopee cushion?
- An amusing thing to catch one who can’t stop talking
- Such on reflection talks over time endlessly?
- Shut up a second! B___ stopping? I hope he is
- Source of much comment as book is restricted by restraining order
- Who’ll cause chatter to falter? Reverse of that
- Boring speaker gets up to talk: a low point
- Gossip airing salacious babble and gossip initially
Buddy explains!

The straight part
We know that "Such on reflection talks over time endlessly" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case such on reflection talks over time endlessly = gasbag.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 GASBAG mean?
GASBAG noun- A bag or bladder to hold a reservoir of gas, as in a hot-air balloon.
- A person who is overly garrulous or prone to making empty, unsupportable statements; a windbag.
- To speak foolishly, pompously, or at length; to blather.