a hard nut to crack

a hard/tough nut to crack

a difficult problem to solve A company whose product has sold well in the States may find the European market a tougher nut to crack.

Name	Pronounced	Usage
Peninnah	pi-NIN-ə (English), pee-NIN-ə (English)	Biblical
Rosetta	[rəu'zetə]
Michelle	[mi'ʃel]
Fabienne	-	French
Enid	['i:nid]
Lamija	-	Bosnian