We present JWST/NIRSpec observations of a highly magnified star candidate at a photometric redshift of \(z_{\mathrm{phot}}\simeq4.8\), previously detected in JWST/NIRCam imaging of the strong lensing (SL) cluster MACS J0647+7015 (\(z=0.591\)). The spectroscopic observation allows us to precisely measure the redshift of the host arc at \(z_{\mathrm{spec}}=4.758\pm0.004\), and the star's spectrum displays clear Lyman- and Balmer-breaks commensurate with this redshift. A fit to the spectrum suggests a B-type super-giant star of surface temperature \(T_{\mathrm{eff,B}}\simeq15000\) K with either a redder F-type companion (\(T_{\mathrm{eff,F}}\simeq6250\)K) or significant dust attenuation (\(A_V\simeq0.82\)) along the line of sight. We also investigate the possibility that this object is a magnified young globular cluster rather than a single star. We show that the spectrum is in principle consistent with a star cluster, which could also accommodate the lack of flux variability between the two epochs. However, the lack of a counter image and the strong upper limit on the size of the object from lensing symmetry, \(r\lesssim0.5\) pc, could indicate that this scenario is somewhat less likely -- albeit not completely ruled out by the current data. The presented spectrum seen at a time when the Universe was only \(\sim1.2\) Gyr old showcases the ability of JWST to study early stars through extreme lensing.