Answer: stumper

AnswerCrossword Clue
STUMPER

Hard-to-answer question

STUMPER

Gordian knot

STUMPER

It's hard to answer

STUMPER
It's not easy
STUMPER
Toughie
STUMPERDifficult question
STUMPERBaffled
STUMPERQuite a puzzle
STUMPERHard-to-solve clue upset Mr. Wilder (7)
STUMPERDifficult problem