Jointly fitting weak lensing, X-ray and Sunyaev-Zel'dovich data to
  constrain scalar-tensor theories with clusters of galaxies
  Degenerate higher-order scalar-tensor (DHOST) theories are considered the
most general class of scalar-tensor theories so that any constraints on them
apply to the full set of scalar-tensor models. DHOST theories modify the laws
of gravity even at galaxy clusters scale hence affecting the weak lensing (WL),
X-ray and Sunyaev-Zel'dovich observables. We derive the theoretical expression
for the lensing convergence $\kappa$, and the pressure profile $P$, of clusters
in the framework of DHOST theories, and quantify how much they deviate from
their General Relativity (GR) counterparts. We argue that combined measurements
of $\kappa$, $P$, and of the electron number density, $n_e$, can constrain both
the cluster and DHOST theory parameters. We carry on a Fisher matrix forecasts
analysis to investigate whether this is indeed the case considering different
scenarios for the spatial resolution and errors on the measured quantities.
