Gaslight first made a mess, then shone (9)
I believe the answer is:
glittered
'shone' is the definition.
('glitter' can be a synonym of 'shine')
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for glittered that I've seen before include "Was like a star" , "Sparkled" , "Was brilliant" .)