A central limit theorem for bilinear forms of the type 90bcb727438cb">, where 0b362bcc52f5fd" title="Click to view the MathML source">a,b∈CN are unit norm deterministic vectors and a robust-shrinkage estimator of scatter parametrized by ρ and built upon n independent elliptical vector observations, is presented. The fluctuations of 90bcb727438cb"> are found to be of order and to be the same as those of for a matrix of a theoretical tractable form. This result is exploited in a classical signal detection problem to provide an improved detector which is both robust to elliptical data observations (e.g., impulsive noise) and optimized across the shrinkage parameter ρ.