  Recent X-ray and Sunyaev-Zel'dovich (SZ) observations have dramatically
increased the number of known distant galaxy clusters. In some merging,
low-redshift (z<0.4) clusters, centrally-located, diffuse, extended radio
emission (called radio halos) has been found. Using the Giant Metrewave Radio
Telescope (GMRT), we report the detection of diffuse radio emission in the
binary-merging cluster PLCK G147.3-16.6 located at z = 0.65. We classify the
emission as a giant radio halo due to the large physical extent of about 0.9
Mpc and low-surface brightness. We measure an integrated flux density of
$7.3\pm1.1$ mJy at 610 MHz for the radio halo, resulting in a 1.4 GHz radio
power of $5.1 \times 10^{24}$ W/Hz. The radio halo power is consistent with
that expected from the known correlation between X-ray luminosity or the
cluster integrated SZ signal and radio power. Our observations also suggest
that more of these distant radio halos could be discovered with the GMRT.
