  Unidirectional spin and charge density wave order in the cuprates is known to
compete with superconductivity. In the stripe order (La,M)$_2$CuO$_4$ family of
cuprates, spin and charge order occur as unidirectional order that can be
stabilized by symmetry breaking structural distortions, such as the low
temperature tetragonal (LTT) phase. Here we examine the interplay between
structure and the formation of charge density wave (CDW) order in the LTT phase
of La$_{1.475}$Nd$_{0.4}$Sr$_{0.125}$CuO$_4$ by applying uniaxial stress to
distort the structure and influence the formation of CDW order. Using resonant
soft x-ray scattering to measure both the CDW order and (0 0 1)
structural-nematic Bragg peaks, we find that the application of uniaxial stress
along the Cu-O bond direction suppresses the (0 0 1) peak and has the net
effect of reducing CDW order, but does so only for CDW order propagating
parallel to the applied stress. We connect these observations to previous work
showing an enhanced superconducting transition temperature under uniaxial
stress; providing insight into how CDW, superconductivity, nematicity, and
structure are related and can be tuned relative to one another in cuprates.
