a hard nut

Meaning

1. 1

   a hard / tough nutinformal

   a person who is difficult to deal with or to influence

2. 2

   a hard / tough nut (to crack)

   a difficult problem or situation to deal with

In the movies · 1

• Hey, come on, Jim. We had one bad test. And it's a hard nut to crack.Daddy Day Care2003

From the same entry

• do your nut
• the nuts and bolts
• off your nut
• use a sledgehammer to crack a nut
• nut out