  We present broadband spectral energy distributions (SEDs) and light curves of
the gamma-ray binary 1FGL J1018.6$-$5856 measured in the X-ray and the
gamma-ray bands. We find that the orbital modulation in the low-energy
gamma-ray band is similar to that in the X-ray band, suggesting a common
spectral component. However, above a GeV the orbital light curve changes
significantly. We suggest that the GeV band contains significant flux from a
pulsar magnetosphere, while the X-ray to TeV light curves are dominated by
synchrotron and Compton emission from an intrabinary shock (IBS). We find that
a simple one-zone model is inadequate to explain the IBS emission, but that
beamed Synchrotron-self Compton radiation from adiabatically accelerated plasma
in the shocked pulsar wind can reproduce the complex multiband light curves,
including the variable X-ray spike coincident with the gamma-ray maximum. The
model requires inclination $\sim$50$^\circ$ and orbital eccentricity
$\sim$0.35, consistent with the limited constraints from existing optical
observations. This picture motivates searches for pulsations from the energetic
young pulsar powering the wind shock.
