clear up vs light up

clear up and light up both are verbs.

Word	Noun	Adjective	Verb	Adverb
clear up	No	No	Yes	No
light up	No	No	Yes	No

As verbs, clear up and light up are synonyms defined as:

Other synonyms of clear up include brighten, clear.

clear up (verb)	light up (verb)
free (the throat) by making a rasping sound	introduce light into
finish a task completely	begin to smoke
make free from confusion or ambiguity; make clear	become clear
make clear and (more) comprehensible	start to burn with a bright flame
become clear	ignite