  We study non-perturbative improvement in SU(3) lattice gauge theory coupled
to fermions in the fundamental and two-index symmetric representations. Our
lattice action is defined with hypercubic smeared links incorporated into the
Wilson-clover fermion kernel. Using standard Schroedinger-functional techniques
we estimate the clover coefficient Csw and find that discretization errors are
much smaller than in thin-link theories.
