The most common and most likely answer to this crossword clue is the 8 letter word ATROCITY
I've seen this crossword clue in The Daily Telegraph
A
T
R
O
C
I
T
Y
More clues leading to the result ATROCITY
- Go round shelled metropolis, causing outrage
- A classical location is host to most of urban massacre?
- Evil rot set in Birmingham?
- Change of rota has municipality in outrage
- Art nouveau associated with old commercial centre is an abomination
- CIA try to resolve crime
- Heinous act at Petrograd, say, involving soldiers after revolution
- Municipality supports change of rota leading to outrage
- Horror witnessed by a townie in Helen’s home?
- I act with Tory somehow to expose this cruelty
Buddy explains!

The straight part
We know that "cruelty" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cruelty = atrocity.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 ATROCITY mean?
ATROCITY noun- An extremely cruel act; a horrid act of injustice.
- The quality or state of being atrocious; enormous wickedness; extreme criminality or cruelty.
- An object considered to be extremely unattractive or undesirable.