  We study the evolutionary path of the Fornax cluster galaxy NGC$~$1436, which
is known to be currently transitioning from a spiral into a lenticular
morphology. This galaxy hosts an inner star-forming disc and an outer quiescent
disc, and we analyse data from the MeerKAT Fornax Survey, ALMA, and the
Fornax3D survey to study the interstellar medium and the stellar populations of
both disc components. Thanks to the combination of high resolution and
sensitivity of the MeerKAT data, we find that the
$\textrm{H}\scriptstyle\mathrm{I}$ is entirely confined within the inner
star-forming disc, and that its kinematics is coincident with that of the CO.
The cold gas disc is now well settled, which suggests that the galaxy has not
been affected by any environmental interactions in the last $\sim1~$Gyr. The
star formation history derived from the Fornax3D data shows that both the inner
and outer disc experienced a burst of star formation $\sim5$ Gyr ago, followed
by rapid quenching in the outer disc and by slow quenching in the inner disc,
which continues forming stars to this day. We claim that NGC$~$1436 has begun
to effectively interact with the cluster environment 5$~$Gyr ago, when a
combination of gravitational and hydrodynamical interactions caused the
temporary enhancement of the star-formation rate. Furthermore, due to the
weaker gravitational binding $\textrm{H}\scriptstyle\mathrm{I}$ was stripped
from the outer disc, causing its rapid quenching. At the same time, accretion
of gas onto the inner disc stopped, causing slow quenching in this region.
