Need to change after illumination is decreased (9)
I believe the answer is:
lightened
'decreased' is the definition.
The answer and definition can be both related to change as well as being past participle verbs.
Maybe you can see a link between them that I can't see?
'need to change after illumination' is the wordplay.
'to change' is an anagram indicator.
'after' is a charade indicator (letters next to each other).
'illumination' becomes 'light' (light is a kind of illumination).
'need' with letters rearranged gives 'ened'.
'ened' after 'light' is 'LIGHTENED'.
'is' is the link.
Can you help me to learn more?
(Other definitions for lightened that I've seen before include "Reduced the weight" , "got more sun perhaps" , "Became less heavy" .)