The most common and most likely answer to this crossword clue is the 9 letter word INGESTION
I've seen this crossword clue in The Times
I
N
G
E
S
T
I
O
N
Buddy explains!

The straight part
We know that "Consumption" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case consumption = ingestion.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.