The most common and most likely answer to this crossword clue is the 8 letter word CULPRITS
I've seen this crossword clue in The Sunday Telegraph
C
U
L
P
R
I
T
S
Buddy explains!

The straight part
We know that "Guilty lot" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case guilty lot = culprits.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 CULPRITS mean?
CULPRITS noun- The person or thing at fault for a problem or crime.
- A prisoner accused but not yet tried.