Gossip here would be a concern, if head is replaced (6)

I believe the answer is:

natter

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'gossip' is the definition.
(I know that gossip can be written as natter)

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for natter that I've seen before include "Talk inconsequentially" , "idle talk" , "Chat - gossip" , "Chat away informally" , "Chit-chat" .)

I've seen this clue in The Times.

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