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
Sparrow	SPAR-o	English (Rare)
Ebru	-	Turkish
Wilkinson	['wilkinsn]
Horia	-	Romanian
Bertha	BER-tah (German), BUR-thə (English)	German, English, Ancient Germanic
Adaeze	-	Western African, Igbo