快刀斩乱麻

kuài dāo zhǎn luàn má

lit. quick sword cuts through tangled hemp (idiom); decisive action in a complex situation

cutting the Gordian knot

kuài

rapid

dāo

knife; blade; single-edged sword; cutlass (CL:把[ba3])

zhǎn

to behead (as form of capital punishment)

luàn

in confusion or disorder

generic name for hemp, flax etc