The most common and most likely answer to this crossword clue is the 9 letter word DERRINGER
I've seen this crossword clue in Financial Times
D
E
R
R
I
N
G
E
R
More clues leading to the result DERRINGER
- Pistol produced by the German impostor
- The German campanologist’s short arm
- Colour transposed on double weapon
- Gun misbehaving? Get embarrassed, upset about it
- Doing wrong wearing the German pistol
- The German admits making mistake providing weapon
- Weapon going wrong held by the German
- Making a mistake in the German gun
- A pistol Ruby returned clipped off finger tip when held by radical
- Gun missing the mark in German article
Buddy explains!

The straight part
We know that "pistol" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case pistol = derringer.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 DERRINGER mean?
DERRINGER noun- A type of very small, concealable pistol with one or two barrels, but without any loading system or magazine.