The most common and most likely answer to this crossword clue is the 9 letter word FIREPOWER
I've seen this crossword clue in The Guardian
F
I
R
E
P
O
W
E
R
More clues leading to the result FIREPOWER
- Army might motivate royalty to keep enemy captive
- A lot of artillery being used to sack country
- Military might prefer, I suspect, to suppress cry of anguish
- I prefer women, not men, to build strength in the military
- Upright cable we must break to support tree’s shooting capability
- French leader with authority conceals displeasure at the effectiveness of a weapon
- Destructive capacity of ignition coupled with strength
- Might I prefer half of wood chopped up?
Buddy explains!

The straight part
We know that "strength in the military" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case strength in the military = firepower.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 FIREPOWER mean?
FIREPOWER noun- The capacity of a weapon to deliver fire onto a target
- The ability to deliver fire
- The ability to shoot and score goals.