  Ultra-steep spectrum (USS) radio sources with complex filamentary
morphologies are a poorly understood subclass of diffuse radio source found in
galaxy clusters. They are characterised by power law spectra with spectral
indices less than -1.5, and are typically located in merging clusters. We
present X-ray and radio observations of the galaxy cluster A272, containing a
USS diffuse radio source. The system is an ongoing major cluster merger with an
extended region of bright X-ray emission south of the core. Surface brightness
analysis yields a $3\sigma$ detection of a merger shock front in this region.
We obtain shock Mach numbers $M_\rho = 1.20 \pm 0.09$ and $M_T = 1.7 \pm 0.3$
from the density and temperature jumps, respectively. Optical data reveals that
the system is a merger between a northern cool core cluster and a southern
non-cool core cluster. We find that the USS source, with spectral index
$\alpha^{\text{74 MHz}}_{\text{1.4 GHz}} = -1.9 \pm 0.1$, is located in the
bright southern region. Radio observations show that the source has a
double-lobed structure with complex filaments, and is centred on the brightest
cluster galaxy of the southern subcluster. We provide two suggestions for the
origin of this source; the first posits the source as an AGN relic that has
been re-energised by the passing of a merger shock front, while the second
interprets the complex structure as the result of two overlapping AGN radio
outbursts. We also present constraints on the inverse Compton emission at the
location of the source.
