Endless crisis, the last arrival (9)
I believe the answer is:
emergence
'arrival' is the definition.
(I know that emergence is a type of appearance)
'endless crisis the last' is the wordplay.
'endless' means to remove the last letter.
'crisis' becomes 'emergency' (emergency is a kind of crisis).
'the last' becomes 'e' (I can't explain this - if you can you should believe this answer much more).
'emergency' with its last letter taken off is 'emergenc'.
'emergenc'+'e'='EMERGENCE'
Can you help me to learn more?
(Other definitions for emergence that I've seen before include "rise" , "First appearance" , "A coming forth" , "Development" , "Sudden appearance" .)