Nonlinear turbulent-shear flow interactions are directly measured in a cylindrical helicon plasma device and found to lead to the development of an azimuthally symmetric radially sheared azimuthal flow by the action of a turbulent Reynolds stress which transfers kinetic energy into the large-scale shear flow. Radially resolved measurements of the nonlinear kinetic energy transfer show that the flow is driven at the plasma boundary; temporally resolved flow measurements show a penetration of the resulting azimuthal flow into the central plasma region. The results provide an initial qualitatively test of theoretical predictions, and suggest how similar studies might be carried out in confinement devices.