English ⇄ Russian +

thorn in the side stresses
	⇒ pain in the arse; pain in the ass; pain in the neck
gen.	бельмо в глазу (r1ng0)
fig.of.sp.	заноза в пятой точке (... has long been a thorn in the side of ... Alex_Odeychuk)

thorn in the side : 1 phrase in 1 subject

Idiomatic

1