The most common and most likely answer to this crossword clue is the 7 letter word SQUALID
I've seen this crossword clue in The Times
S
Q
U
A
L
I
D
More clues leading to the result SQUALID
- Foul initially seen as being over the top
- Repulsive gang getting in the middle of police
- Disgusting gangster swallowed by sea creature
- Dirty team containing one left back
- Unpleasant short story accepted by team
- Group of players defending centre for silliest foul
- Foul seafood covering meal left by me
- Wretched group circling Long Island
- Dreadful company stifling life? Not half
- Foul left one surrounded by team
Buddy explains!

The straight part
We know that "Foul" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case foul = squalid.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 SQUALID mean?
SQUALID adjective- Extremely dirty and unpleasant.
- Showing a contemptible lack of moral standards.
- Any member of the family Squalidae of dogfish sharks.