clue vs leave trace

clue

verb
  • To provide with a clue. 

  • To provide someone with information which he or she lacks (often used with "in" or "up"). 

noun
  • Information which may lead one to a certain point or conclusion. 

  • An object or a kind of indication which may be used as evidence. 

  • Insight or understanding ("to have a clue [about]" or "to have clue". See have a clue, clue stick) 

leave trace

How often have the words clue and leave trace occurred in a corpus of books? (source: Google Ngram Viewer )