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
Franc	-	Slovene
Gisilfrid	-	Ancient Germanic
Birgitte	-	Danish, Norwegian
Cherilyn	SHER-ə-lin	English
Solomon	SAHL-ə-mən (English)	Biblical, English, Jewish
Fadia	-	Arabic