The most common and most likely answer to this crossword clue is the 12 letter word INCENDIARIES
I've seen this crossword clue in Financial Times
I
N
C
E
N
D
I
A
R
I
E
S
Buddy explains!

The straight part
We know that "Explosive devices" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case explosive devices = incendiaries.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 INCENDIARIES mean?
INCENDIARIES noun- Something capable of causing fire, particularly a weapon.
- One who maliciously sets fires.
- One who excites or inflames factions into quarrels.