ZnCr2Se4 is a magnetically frustrated spinel compound with an incommensurate ground state. At low temperatures it displays a spin spiral structure propagating along the (100) direction, and the formation of this state is accompanied by a structural transition, indicating a spin-lattice coupling. Measurements in magnetic field show that this spin-spiral ground state gives way to a separate phase at higher field, which is not well understood and thought to be a spin-nematic state. We propose to map out the magnetic excitation spectrum of this compound in applied magnetic field using the MERLIN spectrometer, and by doing so quantitatively determine the strength of the magnetic interactions, and develop a realistic magnetic Hamiltonian for this material.