The most common and most likely answer to this crossword clue is the 6 letter word WEAPON
I've seen this crossword clue in The Daily Telegraph
W
E
A
P
O
N
More clues leading to the result WEAPON
- One cause of MD being fired may be used in part of 9 18 23 down, 27 1 across
- You and I run away from Border Terrier — or what he might be carrying?
- You and I will have a poncho, not half, only an arm
- Hand turned around sleeve’s end, touching arm
- No seat when turned over is found to conceal a gun?
- Perhaps blunderbuss prevailed in war, having shot pea partway through
- An arm now raised around each softly
- Seat tipped over getting a new arm
- Knife, perhaps, with mushy pea on
- Peashooter, say, with no pea? Useless
Buddy explains!

The straight part
We know that "Peashooter, say" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case peashooter, say = weapon.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 WEAPON mean?
WEAPON noun- An instrument of attack or defense in combat or hunting, e.g. most guns, missiles, or swords.
- An instrument or other means of harming or exerting control over another.
- A tool of any kind.
- An idiot, an oaf, a fool, a tool; a contemptible or incompetent person.