The most common and most likely answer to this crossword clue is the 10 letter word STRIDENTLY
I've seen this crossword clue in The Daily Telegraph
S
T
R
I
D
E
N
T
L
Y
More clues leading to the result STRIDENTLY
- Missile installed in secret using rough force
- Urgently employing craft carrying nuclear weapon
- Angrily listen first of all to dog yapping repeatedly in a shrill way
- In the manner of loud protesters, knowing about nuclear weapon
- A supposedly good person trendily cavorting loudly
- Harshly cunning, holding spear
Buddy explains!

The straight part
We know that "Urgently" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case urgently = stridently.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 STRIDENTLY mean?
STRIDENTLY adverb- In a strident manner.