  We present the discovery of as-of-yet non-repeating Fast Radio Burst (FRB),
FRB 20210117A, with the Australian Square Kilometer Array Pathfinder (ASKAP) as
a part of the Commensal Real-time ASKAP Fast Transients (CRAFT) Survey. The
sub-arcsecond localization of the burst led to the identification of its host
galaxy at a $z=0.214(1)$. This redshift is much lower than what would be
expected for a source dispersion measure (DM) of 729 pc cm$^{-3}$, given
typical contributions from the intergalactic medium and the host galaxy.
Optical observations reveal the host to be a dwarf galaxy with little on-going
star formation, very different to the dwarf host galaxies of known repeating
FRBs 20121102A, and 20190520B. We find an excess DM contribution from the host
and attribute it to the FRB's local environment. We do not find any radio
emission from the FRB site or host galaxy. The low magnetized environment and
lack of a persistent radio source (PRS) indicate that the FRB source is older
than those found in other dwarf host galaxies, and establish the diversity of
FRB sources in dwarf galaxy environments. We find our observations to be fully
consistent with the hypernebula model, where the FRB is powered by
accretion-jet from a hyper-accreting black hole. Finally, our high-time
resolution analysis reveals burst characteristics similar to those seen in
repeating FRBs. We encourage follow-up observations of FRB 20210117A to
establish any repeating nature.
