The most common and most likely answer to this crossword clue is the 4 letter word OGRE
O
G
R
E
More clues leading to the result OGRE
- Occupying zoo, great big monster
- Turn back extremely rude monster
- Man-eating giant therefore returned
- Beast returning hence
- Monster involved in rather gory comeback
- Duck almost became ugly one
- Giant tucking into burrito, greedy
- Monster? Er… Run in the opposite direction!
- Wicked person’s so upset
- Monster seen in bog, recently
Buddy explains!

The straight part
We know that "Monster" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case monster = ogre.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 OGRE mean?
OGRE noun- A type of brutish giant from folk tales that eats human flesh.
- A brutish man reminiscent of the mythical ogre.