clarify vs thrash something out

clarify

verb
  • To grow clear or bright; to clear up. 

  • To make clear or easily understood; to explain in order to remove doubt or obscurity. 

  • To grow or become clear or transparent; to become free from feculent impurities, as wine or other liquid under clarification. 

  • To make clear or bright by freeing from feculent matter. 

thrash something out

How often have the words clarify and thrash something out occurred in a corpus of books? (source: Google Ngram Viewer )