clam up vs persuade

clam up

verb
  • To become silent; to stop talking, to shut up. 

  • To make or become clammy. 

persuade

verb
  • To successfully convince (someone) to agree to, accept, or do something, usually through reasoning and verbal influence. 

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