Series creation developed into a repeating process (5,8)
I believe the answer is:
chain reaction
'process' is the definition.
(chain reaction is a kind of process)
'series creation developed into a repeating' is the wordplay.
I cannot quite see how this works, but
'series' could be 'chain' (chain is a kind of series) and 'chain' is located in the answer.
an anagram of 'creation' is 'reaction' which is present in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for chain reaction that I've seen before include "Self-maintaining process" , "The domino effect?" , "Diana Ross song" , "process hard to stop" , "Series of consequences" .)