Complex sentence: Adenauer, dubbed "Der Alte" ("the old man"), the oldest leader in a democracy in history (was still Chancellor at age 87.), belied his age by his intense work habits and his uncanny political instinct.
Split into simpler sentences: Adenauer, dubbed "Der Alte" ("the old man"), the oldest leader in a democracy in history, was still Chancellor at age 87. He belied his age by his intense work habits and his uncanny political instinct.