Tough nut to crack Crossword Clue

Other answers seen for this clue

• ACORN5 letters

  answer page
  Appeared in 2 New York Times Crosswords between February 2015 and June 2021.
• POSER5 letters

  answer page
  Appeared in 1 New York Times Crossword: Friday, May 26, 2023.
• PECAN5 letters

  answer page
  Appeared in 1 New York Times Crossword: Saturday, December 1, 2012.

• Cipher machine of W.W. II

  New York Times · Tuesday, July 23, 2024 · 6 letters

• Riddle

  New York Times · Monday, February 12, 2024 · 6 letters

• Very secretive sort

  New York Times · Wednesday, September 7, 2022 · 6 letters

• Personality that's hard to read

  New York Times · Sunday, October 24, 2021 · 6 letters

• Monthly publication of the National Puzzlers' League, with "The"

  New York Times · Sunday, August 15, 2021 · 6 letters

• Conundrum

  New York Times · Monday, November 30, 2020 · 6 letters

• Puzzle

  New York Times · Wednesday, September 30, 2020 · 6 letters

• Mystery

  New York Times · Sunday, February 4, 2018 · 6 letters

• The Mona Lisa's smile, e.g.

  New York Times · Saturday, October 21, 2017 · 6 letters

• Nazi cipher machine broken by the Allies

  New York Times · Wednesday, November 18, 2015 · 6 letters

More clues from this crossword

• 38-Down Catchphrase for moviedom's "International Man of Mystery"
• 39-Down Vikings, e.g.
• 40-Across Acting unconsciously
• 41-Across Prevailing spirit
• 42-Down "That'll show ya!"
• 43-Across Game piece in Mastermind
• 43-Down Buns
• 45-Down Fitness fanatic, in slang
• 46-Across Legislative subject of the 2020 miniseries "Mrs. America," for short
• 47-Across Spain's longest river
• 48-Across (NE)OLITH
• 49-Down What seers read