Here are the possible solutions for city of light informally clue
Answer
Clue
Relevancy
paree
Clue
City of Light, informally
glorybeam
Clue
"The light" of "I saw the light!"?
laser
Clue
Light in a light show
Light-show light
Light show light
Light in a light show, perhaps
Definition
a source of high-intensity optical, infrared, or ultraviolet radiation produced as a result of stimulated emission maintained within a solid, liquid, or gaseous medium