Complex sentence: In 1987, the Political Soldier group fell out with Ian Stuart, the lead singer of Skrewdriver, who responded by setting up his own "independent" group, Blood & Honour, whose eponymous publication openly attacked his former NF associates.
Split into simpler sentences: In 1987, the Political Soldier group fell out with Ian Stuart, the lead singer of Skrewdriver. Stuart responded by setting up his own group, Blood & Honour, whose eponymous publication openly attacked his former NF associates.