Complex sentence: She oversaw Hisoka's match with Kastro in the Celestial Tower adn afterward sewed both of Hisoka's arms back to perfect shape with her nen ability, however she does this solely because Hisoka is paying her for the work.
Split into simpler sentences: She oversaw Hisoka's match with Kastro in the Celestial Tower. Afterwards, she sewed both of Hisoka's arms back to perfect shape with her nen ability, however she does this solely because Hisoka is paying her for the work.