Appear as mere chaos at some stage (6)
I believe the answer is:
emerge
'appear' is the definition.
(emerge can mean to appear or arrive)
'mere chaos at some stage' is the wordplay.
'chaos' is an anagram indicator.
'at some stage' becomes 'ge' (I am not sure about this - if you are sure you should believe this answer much more).
'mere' anagrammed gives 'emer'.
'emer'+'ge'='EMERGE'
'as' acts as a link.
Can you help me to learn more?
(Other definitions for emerge that I've seen before include "Rise to notice" , "Issue" , "Come out or become known" , "Break out (from an egg)" , "Move out and become visible" .)