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 ( \sim 3.7 d and \sim 1250 s , respectively ) .
Our observations , for a total of \sim 43 ks , 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 \sim 5 \times 10 ^ { 16 } g to 10 ^ { 21 } g. Our data suggest , based on the X-ray behaviour , that this is an intermediate SFXT .