The most common and most likely answer to this crossword clue is the 8 letter word SCOFFING
I've seen this crossword clue in The Times
S
C
O
F
F
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G
Buddy explains!
The straight part
We know that "Mocking" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case mocking = scoffing.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 SCOFFING mean?
SCOFFING verb- To jeer; to laugh with contempt and derision.
- To mock; to treat with scorn.
- To eat food quickly.
- To eat.
- The act of one who scoffs; derision; mockery.