if you had payed attention to the anime, clare is not a normal claymore, shes only 1/4 yoma, and the flesh that was put in her was former #1 Teresa of the faint smile, so you should suppose that Clare has a very strong yoki in her, though its less then the rest, there's also that Clare has former #2 (or 3 if u count that priscilla took #2) Irene's arm on her, which has a stronger yoki prescence, basically because its 1/2 yoma not 1/4, besides the point, Clare goes into pure anger against Priscilla for killing Teresa and unleashes what i would guess to be all her Yoki, she is lucky she could control it as much as she did, and that jeane was able to return her human before dying, because Raki couldn't this time around.