Chabahar is a tough nut to crack.

Source: https://www.lewrockwell.com/2023/05/no_author/the-inside-story-of-russia-iran-india-connectivity/

Chloe recognised the Super Falcons threat and predicted they will be a tough nut to crack.

Source: https://www.completesports.com/2023-wwc-england-forward-chloe-wary-of-difficult-opponent-super-falcons/

He elaborated, "I'm just kind of a tough nut to crack when it comes to intimacy.

Source: https://www.realitytvworld.com/news/big-brother-evictee-cory-wurtenberger-shares-his-america-lopez-relationship-plans-33124.php

One would assume you might be elated that a tough nut to crack appears to have been solved.

Source: https://www.forbes.com/sites/lanceeliot/2023/11/26/about-that-mysterious-ai-breakthrough-known-as-q-by-openai-that-allegedly-attains-true-ai-or-is-on-the-path-toward-artificial-general-intelligence-agi/

The teenage market for apps is a tough nut to crack and stay relevant in. Just ask Snapchat.

Source: https://techcrunch.com/2023/01/19/german-teens-went-crazy-for-this-compliments-app-and-now-vcs-are-backing-its-next-phase/