The most common and most likely answer to this crossword clue is the 6 letter word RUN-ON
R
U
N
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O
N
Buddy explains!
The straight part
We know that "Talk at length" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case talk at length = run-on.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 RUN-ON mean?
RUN-ON noun- (etc.) An amount of time spent playing on the field during a game, especially so as to evaluate a player's abilities.
- A run-on sentence.
- Anything that runs on, such as a run-on entry in a dictionary.
- The period when a power saw or other tool continues to run after being powered off.
- Continuing on where a rhetorical pause would be more appropriate.
- Placed or coming at the end of something, such as at the end of a dictionary entry.