The most common and most likely answer to this crossword clue is the 10 letter word BOMBARDIER
I've seen this crossword clue in The Daily Telegraph
B
O
M
B
A
R
D
I
E
R
More clues leading to the result BOMBARDIER
- Soldier recalled touching book without one dull moment
- Engineer Bob married NCO in artillery
- Revolutionary mob joins local girl to meet the Queen’s officer
- Artillery officer‘s foolish raid in Wellington, perhaps
- Organised IRA demob British junior officer
- Airman‘s heading off stronger after personal problem seen by doctor
- Gunner’s jacket, perhaps worn over sleeveless cardie
Buddy explains!

The straight part
We know that "Artillery officer" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case artillery officer = bombardier.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 BOMBARDIER mean?
BOMBARDIER noun- A bomber crew member who sights and releases bombs.
- A non-commissioned officer rank in artillery, equivalent to corporal. Abbreviated Bdr.
- An artilleryman; a gunner.
- A bombardier beetle.