The most common and most likely answer to this crossword clue is the 5 letter word MAFIA
I've seen this crossword clue in The Daily Telegraph
M
A
F
I
A
More clues leading to the result MAFIA
- Organised criminals intend rising about a fine
- Criminal organisation’s aim to take in footballers all round?
- West Side Story heroine, fine for Romeo in criminal group
- Mob‘s intention to hold absolutely nothing back
- Chiefly murderers and felons in alliance
- Marie’s head a judicial warrant cut, for the mob?
- Top rate celebrity snubbed and upset the mob
- Mob always fraternised in America initially
- ‘Mob‘ arousing fear in America initially
- Perfect half of family raised in criminal society
Buddy explains!

The straight part
We know that "criminal gang" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case criminal gang = mafia.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 MAFIA mean?
MAFIA noun- A hierarchically structured secret organisation engaged in illegal activities like distribution of narcotics, gambling and extortion.
- A crime syndicate.
- A trusted group of associates, as of a political leader.
- (in compound terms such as "moral mafia") An entity which attempts to control a specified arena.