Complex sentence: He denied the accusations and offered to stand trial, but the Athenians did not want to disrupt the expedition any further and his opponents were eager to accuse him in his absence when he could not defend himself.
Split into simpler sentences: He denied the accusations and offered to stand trial, but the Athenians did not want to disrupt the expedition any further. His opponents were eager to have Alcibiades' trial in his absence when he could not defend himself.