Grew complex (8)
I believe the answer is:
advanced
This might be a double definition.
'grew' is the first definition.
The answer and definition can be both related to change as well as being past participle verbs.
Perhaps there's an association between them I don't understand?
'complex' is the second definition.
(I've seen this before)
Can you help me to learn more?
(Other definitions for advanced that I've seen before include "Far ahead in development or progress" , "Lent - ahead in development" , "Complex; very modern" , "promoted" , "Proposed" .)