External leg amputation in conformal-invariant three-point function

Amputation of external legs is carried out explicitly for the conformal-invariant three-point function involving two spinors and one vector field. Our results are consistent with the general result that amputating an external leg in a conformal-invariant Green function replaces a field by its conformal partner in the Green function. A new star-triangle relation, involving two spinors and one vector field, is derived and used for the calculation.