  We study the scalar-tensor-tensor non-Gaussian signal in an inflationary
model comprising also an axion coupled with SU(2) gauge fields. In this set-up,
metric fluctuations are sourced by the gauge fields already at the linear level
providing an enhanced chiral gravitational waves spectrum. The same mechanism
is at work in generating an amplitude for the three-point function that is
parametrically larger than in standard single-field inflation.
