Although it is well known that the bulk of dark matter (DM) has to be cold, the existence of an additional sub-dominant, hot species remains a valid possibility. In this paper we investigate the potential of the cosmic shear power spectrum to constrain such a mixed (hot plus cold) DM scenario with two additional free parameters, the hot-to-total DM fraction (fhdm) and the thermal mass of the hot component (mhdm). Running a Bayesian inference analysis for both the Kilo-Degree Survey cosmic shear data (KiDS-1000) as well as the cosmic microwave background (CMB) temperature and polarisation data from Planck, we derive new constraints for the mixed DM scenario. We find a 95% confidence limit of fhdm 0:08 for a very hot species of mhdm ≤ 20 eV. This constraint is weakened to fhdm 0:25 for mhdm ≤ 80 eV. Scenarios with masses above mhdm ∼ 200 eV remain unconstrained by the data. Next to providing limits, we investigate the potential of mixed DM to address the clustering (or S 8) tension between lensing and the CMB. We find a reduction of the 2D (Ω m-S 8) tension from 2.9σ to 1.6σ when going from a pure cold DM to a mixed DM scenario. When computing the 1D Gaussian tension on S 8 the improvement is milder, from 2.4σ to 2.0σ.