Radiate, as light (4)
'radiate as light' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for emit that I've seen before include "Give off or discharge" , "Conductor; telegram (US)" , "Make audible sounds" , "shed" , "Small turtle" .)
(Other definitions for mit that I've seen before include "German associated with" , "Cambridge University, initially" .)