The most common and most likely answer to this crossword clue is the 9 letter word EUMENIDES
I've seen this crossword clue in The Times
E
U
M
E
N
I
D
E
S
More clues leading to the result EUMENIDES
- Some union workers — that is, mostly, monsters
- Vengeful trio of Brussels bureaucrats, say, having day in Rome
- Community workers side with morphing, vengeful trio
- Vengeful goddesses appearing nude – I seem discombobulated!
- Community workers side with morphing monsters
- Mythic figures from Greece need muse, I suspect
Buddy explains!
The straight part
We know that "Vengeful trio" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vengeful trio = eumenides.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.