expression, ichidan verb
threaten; intimidate with a menacing tone
Used when someone speaks or acts in a threatening manner, often with a low, menacing voice. The phrase literally means 'to make one's 'dosu' effective,' where 'dosu' is slang for a threatening attitude or voice.
See also: ドスの効いた声
彼はドスを効かせて「金を出せ」と言った。
He threatened, 'Hand over the money,' in a menacing voice.
あのヤクザはいつもドスを効かせた声で話す。
That yakuza always speaks with a threatening tone.