  The evidences for the influence of thermonuclear (type-I) X-ray bursts upon
the surrounding environments in neutron star low-mass X-ray binaries (LMXB)
were detected previously via spectral and timing analyses. Benefitting from a
broad energy coverage of Insight-HXMT, we analyze one photospheric radius
expansion (PRE) burst, and find an emission excess at soft X-rays. Our spectral
analysis shows that, such an excess is not likely relevant to the disk
reflection induced by the burst emission and can be attributed to an enhanced
pre-burst/persistent emission. We find that the burst and enhanced persistent
emissions sum up to exceed Eddington luminosity by $\sim$ 40 percentages. We
speculate that the enhanced emission is from a region beyond the PRE radius, or
through the Comptonization of the corona.
