Complex sentence: John Robie (Cary Grant) is a notorious but retired jewel thief or "cat burglar," nicknamed "The Cat," who now tends to his vineyards in the South of France.
Split into simpler sentences: John Robie (Cary Grant) is a notorious but retired jewel thief or "cat burglar", nicknamed "The Cat". He now spends his time tending to his vineyards in the South of France.