  We present a new investigation of the Cloverleaf (z$=$2.56) based on the
HST/WFPC2, IRAM and CFHT/FOCAM images data. The WFPC2 data shows a significant
overdensity of galaxies around the Cloverleaf that we interpret as the presence
of a distant cluster of galaxies along the line of sight. The Cloverleaf is
probably the result of the lensing effects which include, in addition to a
single galaxy, a distant clusters of galaxies. We have modelled the lens
accordingly. The high-resolution IRAM/CO map provides the orientation and the
ellipticity of the CO spots induced by the shear component. Velocity-positional
effects are detected at the 8$\sigma$ level in the CO map. A strong limit can
then be put on the size, shape and location of the CO source around the quasar.
  The CO source is found to form a disk- or ring- structure orbiting the
central engine at $\sim$ 100km/s at a radial distance of $\sim$ 100pc, leading
to a central mass of $\sim$ 10$^{9}$ M$_\odot$ possibly in the form of a black
hole.
