The most common and most likely answer to this crossword clue is the 9 letter word EMERGENCE
I've seen this crossword clue in The Guardian
E
M
E
R
G
E
N
C
E
More clues leading to the result EMERGENCE
- Coming endless crisis? Not the last for EU
- Coming out, soldiers picked up some DNA around clubs
- Development of endless crisis with Spain
- Church backs drug workers hosting work unit for Advent
- The appearance of endless crisis beginning to extend
- Unfolding crisis after cutting energy
- Rise and unite to break barricade after force leaves
- Coming out of endless crisis with energy
Buddy explains!

The straight part
We know that "Development" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case development = emergence.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 EMERGENCE mean?
EMERGENCE noun- The act of rising out of a fluid, or coming forth from envelopment or concealment, or of rising into view; sudden uprising or appearance.
- In particular: the arising of emergent structure in complex systems.
- An emergency.