The most common and most likely answer to this crossword clue is the 9 letter word INGESTION
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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 INGESTION mean?
INGESTION noun- The action of ingesting, or consuming something orally, whether it be food, drink, medicine, or other substance. It is usually referred to as the first step of digestion.