  We suggest that "Godzilla", an intriguing source in the lensed Sunburst
galaxy at $z=2.37$, is a young super star cluster powering a compact nebula
within gravitationally trapped stellar ejecta. Employing HST photometry and
spectroscopy from MUSE and X-Shooter at VLT, we infer physical and chemical
properties of the cluster and nebula, finding Godzilla is young (4-6 Myr),
massive ($\sim 10^{6-7}M_\odot$), a stellar metallicity $Z \simeq 0.25Z_\odot$,
and has the FUV component more compact than a few pc. The nebula gas is
significantly enriched with N and He, indicating stellar wind material, and has
highly elevated O relative to the sub-solar stellar metallicity, which
indicates entrainment of CCSNe ejecta. The high gas density $n_{\rm e} \simeq
10^{7-8}{\rm cm}^{-3}$ implies a highly pressurized intracluster environment.
We propose the high pressure is due to CCSN-driven supersonic turbulence in
warm, self-shielding gas, which has accumulated in the cluster center after
runaway radiative cooling and is dense enough to resist removal by CCSNe. The
nebula gas shows sub-solar C/O, Ne/O and Si/O values, which may reflect the
CCSN element yields for initial stellar masses $>40M_\odot$. A comparison to
element yield synthesis models for young star clusters shows that the gas
abundance pattern is consistent with complete retention and mixture of stellar
winds and CCSNe ejecta until the inferred cluster age. The O and He enhancement
we find may have implications for the formation of multiple stellar populations
in globular clusters, as Godzilla likely has already formed second-generation
stars prior to the onset of CCSNe and evolved star winds, in order not to
contradict the non-observation of O and large He enhancement in
second-generation stars.
