Complex sentence: In his eighth play that he wrote, no girl would act because the earlier seven had been miserable flops but the eighth went on to win a prize because through his persistent writing he had found a way of engaging story-telling.
Split into simpler sentences: In his eighth play that he wrote, no girl would act because the earlier seven had been miserable flops. But the eighth one was not only interesting but it went on to win a prize in the competition he had entered; through his persistent writing he had found a way of engaging story-telling.