  Studying galaxy clusters through their Sunyaev-Zel'dovich (SZ) imprint on the
Cosmic Microwave Background has many important advantages. The total SZ signal
is an accurate and precise tracer of the total pressure in the intra-cluster
medium and of cluster mass, the key observable for using clusters as
cosmological probes. Band 5 observations with SKA-MID towards cluster surveys
from the next generation of X-ray telescopes such as e-ROSITA and from Euclid
will provide the robust mass estimates required to exploit these samples. This
will be especially important for high redshift systems, arising from the SZ's
unique independence to redshift. In addition, galaxy clusters are very
interesting astrophysical systems in their own right, and the SKA's excellent
surface brightness sensitivity down to small angular scales will allow us to
explore the detailed gas physics of the intra-cluster medium.
