Wiktionary
n. (alternative form of tough nut to crack English)
Usage examples of "tougher nut to crack".
Nor was the King's Tower strongest - the Tower of Guards beside the kingsroad would be a tougher nut to crack.
Because of its more massive nickel-iron core, Molakar was a tougher nut to crack than Cible had been.
Art would be a tougher nut to crack, but there was a good possibility he would see reason, once I got him past the first awful hurdle.
But Ryld, with this strange infatuation with her soon-to-be-former mistress, would be a tougher nut to crack.
If the Irish and Britons had managed to ally themselves against the Saxons and Angles and Jutes, not only would the invaders have found Britain a tougher nut to crack, the Anglo-Saxon kings and their English descendants wouldn't have existed to invade Ireland several hundred years later—.