The most common and most likely answer to this crossword clue is the 8 letter word MINOTAUR
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More clues leading to the result MINOTAUR
- Monster ran out, I'm shaking!
- Semi-human creature Greek character encountered in youth
- Greek character pinned by relatively insignificant monster …
- Greek character breaks petty Cretan cross
- New trio with Man United’s legendary menace
- Slight hill some say is a monster
- Hybrid child receiving letter from Athens
- Unimportant that Greek character cuts monster
- Monster Greek character encountered in youth
- 50 per cent ruminant changed to 75 per cent of ruminant
Buddy explains!

The straight part
We know that "50 per cent ruminant" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case 50 per cent ruminant = minotaur.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.