The most common and most likely answer to this crossword clue is the 4 letter word YACK
I've seen this crossword clue in Independent
Y
A
C
K
More clues leading to the result YACK
Buddy explains!

The straight part
We know that "Talk" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case talk = yack.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 YACK mean?
YACK noun- A talk, particular an informal talk; chattering; gossip.
- A laugh.
- Vomit.
- To talk, particularly informally but persistently; to chatter or prattle.
- To vomit, usually as a result of excessive alcohol consumption.
- (possibly obsolete) An oak.