  Galaxy clusters could produce gamma-rays from inverse Compton scattering of
cosmic ray electrons or hadronic interactions of cosmic ray protons with the
intracluster medium. It is still an open question on whether gamma-ray emission
($>$ GeV energies) has been detected from galaxy clusters. We carry out a
systematic search for gamma-ray mission based on 300 galaxy clusters selected
from the 2500 deg.$^2$ SPT-SZ survey after sorting them in descending order of
$M_{500}/z^2$, using about 15 years of Fermi-LAT data in the energy range
between 1-300 GeV. We were able to detect gamma-ray emission with significance
of about $6.1\sigma$ from one cluster, viz SPT-CL J2012-5649. The estimated
photon energy flux from this cluster is approximately equal to $1.3 \times
10^{-6}$ MeV cm$^{-2}$ s$^{-1}$. The gamma-ray signal is observed between
$1-10$ GeV with the best-fit spectral index equal to $-3.61 \pm 0.33$. However,
since there are six radio galaxies spatially coincident with SPT-CL J2012-5649
within the Fermi-LAT PSF, we cannot rule out the possibility this signal could
be caused by some of these radio galaxies. Six other SPT-SZ clusters show
evidence for gamma-ray emission with significance between $3-5\sigma$. None of
the remaining clusters show statistically significant evidence for gamma-ray
emission.
