  We present the results from an analysis of data from an \textit{XMM-Newton}
observation of the accreting high mass X-ray binary pulsar GX 301$-$2. Spectral
analysis in the non-flaring segment of the observation revealed that the
equivalent width of the iron fluorescence emission is correlated with the
observed absorption column density and the ratio of the iron K$\beta$ and
K$\alpha$ line strength varied with the flux of the source. Coherent pulsations
were detected with the spin period of the pulsar of 687.9$\pm$0.1 s, and a
secondary pulsation was also detected with a period of 671.8$\pm$0.2 s, most
prominent in the energy band of the iron line. At the spin period of the
neutron star, the pulsation of the iron line has a low amplitude and the
profile is different from the continuum. Pulse phase-resolved spectroscopy also
revealed pulsations of the iron emission line during the non-flaring segment of
the light curve. At the secondary period, both the iron line and the continuum
have nearly identical pulse fraction and pulse profile. The additional
periodicity can be attributed to the beat frequency between the spin of the
neutron star and the Keplerian frequency of a stellar wind clump in retrograde
motion around the neutron star. Reprocessed X-ray emissions originating from
the clump can produce the observed secondary pulsations both in the continuum
and the iron fluorescence line. The clump rotating around the neutron star is
estimated to be approximately five lt-s away from the neutron star.
