Shell very small, 4 mm, light weight, high spire. Protoconch smooth, globose, 2 whorls, 0.36 mm high, 0.58 wide. 4 teleoconch whorls. Suture impressed, nearly straight. Whorls turreted at an angle declining to the left. About 12 strong, thin axial ribs per whorl. Start just below suture but are initially faint; subsutural area may appear to be a spiral cord. Ribs peak just above centre of whorl, tend to match on adjacent whorls. Final rib of body whorl swollen into a varix. Outer lip thickened. Sinus deep, U shaped. Callus absent. Columella thin, slightly callused. Shell truncate, anterior canal short, broad, shallow. Aperture "rectangular. Colour glossy white in dead collected specimens. Length 3,8 mm; Width 1,7 mm.

At first inspection Clavus hewittae appears to be closest to Guraleus flavescens Angas, 1877 from off New South Wales. However Clavus hewittae has a lower spire, more prominent and more numerous ribs and a more flared outer lip.

81-276 m depth, Recherche Archipelago to northwest of Beagle I., Western Australia. Type location: 139 m depth. Direction Bank, off Rottnest I