  We report the presence of high significance diffuse radio emission from the
Triangulum Australis cluster using observations made with the KAT-7 telescope
and propose that this emission is a giant radio halo. We compare the radio
power from this proposed halo with X-ray and SZ measurements and demonstrate
that it is consistent with the established scaling relations for cluster
haloes. By combining the X-ray and SZ data we calculate the ratio of
non-thermal to thermal electron pressure within Triangulum Australis to be
$X=0.658\pm0.054$. We use this ratio to constrain the maximum magnetic field
strength within the halo region to be $B_{\rm max, halo} = 33.08\,\mu$G and
compare this with the minimum field strength from equipartition of $B_{\rm min,
halo} = 0.77(1+k)^{2/7}\,\mu$G to place limits on the range of allowed magnetic
field strength within this cluster. We compare these values to those for more
well-studied systems and discuss these results in the context of equipartition
of non-thermal energy densities within clusters of galaxies.
