The most common and most likely answer to this crossword clue is the 8 letter word INTERPOL
I've seen this crossword clue in The Sunday Telegraph
I
N
T
E
R
P
O
L
More clues leading to the result INTERPOL
- Let rip on corrupt cross-border force
- Peril not unusual for crime fighters
- Lone trip devised for anti-crime organisation
- Organisation helping forces put Underground staff out of terminal
- Trainee not quite joining reduced staff in crime busting force
- Form of protein and mineral ultimately joined forces
- Topliner running police force
- Peril not problematical for group seeking criminals
- Insert cutting digested for detectives
- Police around the world corrupt? Not worried
Buddy explains!
The straight part
We know that "joined forces" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case joined forces = interpol.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.