Complex sentence: By 1914 Sylvia had many disagreements with the route the WSPU was taking: while the WSPU had become independent of any political party, she wanted an explicitly socialist organisation tackling wider issues than women's suffrage, aligned with the Independent Labour Party.
Split into simpler sentences: By 1914 Sylvia had many disagreements with the route the WSPU was taking. It had become independent of any political party, but she wanted it to become an explicitly socialist organisation tackling wider issues than women's suffrage, and aligned with the Independent Labour Party.