The most common and most likely answer to this crossword clue is the 12 letter word FERMENTATION
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More clues leading to the result FERMENTATION
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The cryptic/wordplay part
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What does FERMENTATION mean?
FERMENTATION noun- Any of many anaerobic biochemical reactions in which an enzyme (or several enzymes produced by a microorganism) catalyses the conversion of one substance into another; especially the conversion (using yeast) of sugars to alcohol or acetic acid with the evolution of carbon dioxide
- A state of agitation or excitement; a ferment.