The most common and most likely answer to this crossword clue is the 8 letter word STARVING
I've seen this crossword clue in The Guardian
S
T
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Buddy explains!

The straight part
We know that "Ravenous" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ravenous = starving.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 STARVING mean?
STARVING verb- To die; in later use especially to die slowly, waste away.
- To die because of lack of food or of not eating.
- To be very hungry.
- To destroy, make capitulate or at least make suffer by deprivation, notably of food.
- To deprive of nourishment or of some vital component.
- To deteriorate for want of any essential thing.
- (especially Yorkshire and Lancashire) To kill with cold.
- Starvation