The most common and most likely answer to this crossword clue is the 7 letter word INHUMAN
I've seen this crossword clue in Independent
I
N
H
U
M
A
N
More clues leading to the result INHUMAN
- Brutal Scotsman masking new and unpleasant whiff
- Cruel chums stripped man naked in pub
- The majority of stupid guards make droning sound, being cruel
- Sadistic alien?
- Animal‘s pong accepted by one elderly relative
- Animal smell, not pleasant, over area in pub
- Brutal throbbing advanced, nursed by local
- Animal watering hole in which smell’s appalling at first
- Popular and hard unionist chap getting brutal
- Animal purring by a fenced-in watering hole
Buddy explains!

The straight part
We know that "Cruel" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cruel = inhuman.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 INHUMAN mean?
INHUMAN adjective- Of or pertaining to inhumanity and the indifferently cruel, sadistic or barbaric behavior it brings.