The most common and most likely answer to this crossword clue is the 12 letter word CONFECTIONER
I've seen this crossword clue in The Daily Telegraph
C
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N
F
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C
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More clues leading to the result CONFECTIONER
Buddy explains!

The straight part
We know that "One responsible for producing humbug among others?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one responsible for producing humbug among others? = confectioner.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 CONFECTIONER mean?
CONFECTIONER noun- A manufacturer of or dealer in confections.