The most common and most likely answer to this crossword clue is the 5 letter word LATHI
I've seen this crossword clue in Financial Times
L
A
T
H
I
More clues leading to the result LATHI
- In Bhopal, a thick, long, heavy stick
- In Bengal, a thick club
- Note about husband supporting US city club
- it may give character at heart of mêlée a nasty hit
- Weapon used by police in Eilat, historically
- Letters from Plath implicating Indian police enforcer
- Left injured, hit with a stick
- Partially reveal a thick stick
- Weapon used by police in control at Hibs
- “Some characters to kill at …” — Hitchcock getting stick
Buddy explains!

The straight part
We know that "Weapon" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case weapon = lathi.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 LATHI mean?
LATHI noun- A heavy stick or club, usually used by policemen.
- A martial art based on stick fighting originally practiced in India.