Answer: POSER

The word "poser" can have multiple meanings, but in the context of being a "tough nut to crack," it typically refers to someone who pretends to be something they're not, often in order to gain attention or admiration. It implies a person who tries to give off a false impression of confidence, knowledge, or skill, but when challenged or questioned, they struggle to back up their claims. So, in this case, a "poser" is someone who is difficult to figure out or understand, making them a challenging person to unravel or decode.

Note: The provided meaning of the answer is for the latest New York Times crossword puzzle clue: Wannabe. Explanations are generated by AI and may be inaccurate.