  Nanoelectronic hybrid devices combining superconductors and a one-dimensional
nanowire are promising platforms to realize topological superconductivity and
its resulting exotic excitations. The bulk of experimental studies in this
context are transport measurements where conductance peaks allow to perform a
spectroscopy of the low lying electronic states and potentially to identify
signatures of the aforementioned excitations. The complexity of the
experimental landscape calls for a benchmark in an elemental situation. The
present work tackles such a task using an ultra-clean carbon nanotube circuit.
Specifically, we show that the combination of magnetic field, weak disorder and
superconductivity can lead to states clustering at low energy, as predicted by
the random matrix theory predictions. Such a phenomenology is very general and
should apply to most platforms trying to realize topological superconductivity
in 1D systems, thus calling for alternative probes to reveal it.
