  We present new 0.6 - 4 $\mu$m imaging of the SR 21 transition disk from
Keck/NIRC2 and Magellan/MagAO. The protoplanetary disk around SR 21 has a large
(~ 30 - 40 AU) clearing first inferred from its spectral energy distribution
and later detected in sub-millimeter imaging. Both the gas and small dust
grains are known to have a different morphology, with an inner truncation in CO
at ~7 AU, and micron-sized dust detected within the millimeter clearing.
Previous near-infrared imaging could not distinguish between an inner dust disk
with a truncation at ~7 AU or one that extended to the sublimation radius. The
imaging data presented here require an inner dust disk radius of a few AU, and
complex structure such as a warp or spiral. We present a parametric warped disk
model that can reproduce the observations. Reconciling the images with the
spectral energy distribution gathered from the literature suggests grain growth
to ~2 - 5 $\mu$m within the sub-millimeter clearing. The complex disk structure
and possible grain growth can be connected to dynamical shaping by a
giant-planet mass companion, a scenario supported by previous observational and
theoretical studies.
