The most common and most likely answer to this crossword clue is the 4 letter word AMMO
I've seen this crossword clue in The Guardian
A
M
M
O
More clues leading to the result AMMO
- Projectiles initially manufactured in a very short time
- Confession from doctor that goes in magazine: ...?
- Army doctor introducing himself, making rounds
- Rounds of smoked ham, skinned
- Magazine content from magazine about bags
- Bullets held back by commando
- I’m fired, found lying in hammock
- Rounds with ham, more sandwiches
- Shot of William Morris
- Modus operandi topped by morning rounds
Buddy explains!

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 AMMO mean?
AMMO noun- Ammunition.
- To load up on ammunition.