clear up vs illustrate

clear up

verb
  • To clarify, to correct a misconception. 

  • To depart or disappear. 

  • To clean up. 

  • To become free of certain blemishes. 

  • Of stormy weather, to dissipate, to become calm. 

  • To pot all of the remaining balls in a single turn. 

illustrate

verb
  • To clarify something by giving, or serving as, an example or a comparison. 

  • To provide a book or other publication with pictures, diagrams or other explanatory or decorative features. 

How often have the words clear up and illustrate occurred in a corpus of books? (source: Google Ngram Viewer )