  We report on the Swift monitoring of the candidate supergiant fast X-ray
transient (SFXT) IGR J16418-4532, for which both orbital and spin periods are
known (~3.7d and ~1250s, respectively). Our observations, for a total of ~43ks,
span over three orbital periods and represent the most intense and complete
sampling of the light curve of this source with a sensitive X-ray instrument.
With this unique set of observations we can address the nature of this
transient. By applying the clumpy wind model for blue supergiants to the
observed X-ray light curve, and assuming a circular orbit, the X-ray emission
from this source can be explained in terms of the accretion from a spherically
symmetric clumpy wind, composed of clumps with different masses, ranging from
~5E16 g to 1E21g. Our data suggest, based on the X-ray behaviour, that this is
an intermediate SFXT.
