We have observed nine Wolf-Rayet galaxies at 20,6, 3.6 and 2 cm from the VLA and at Hα from the Wise Observatory, and have mapped the radio spectral index in each galaxy on sub-arcsec scales. We find that more than half the WR sample has distinct regions where the radio spectrum rises between 6 and 2 cm. We believe that this is the radio signature of the youngest super-star-clusters which are otherwise invisible, and which require N
Lyc ≳ 1052, or equivalent to 750 stars of the 07 subtype. We call these sources radio super-star-clusters.