We study the radiation environment near the THz dump of the CLEAR electron accelerator at CERN, using FLUKA simulations and Single Event Upset measurements taken with 32 Mbit ISSI SRAM memories. The main focus is on the characterisation of the neutron field, to evaluate its suitability for radiation tests of electronics in comparison with other irradiation facilities. Neutrons at CLEAR are produced via photonuclear reactions, mostly initiated by photons from the electromagnetic cascades that occur when the beam is absorbed by the dump structure. Good agreement is generally found between the measured SEU rates and the expected values obtained from FLUKA simulations and from the known SEU response of the ISSI SRAMs to neutrons, while one position is found to be potentially affected by photon-driven SEUs.