Complex sentence: The role of Anarkali had first been offered to Suraiya; but although Madhubala had acted in a number of films and was considered to be in the twilight of her career, she was longing for a significant role.
Split into simpler sentences: The role of Anarkali had first been offered to Suraiya. Though Madhubala had acted in a number of films and was considered to be in the twilight of her career, she was longing for a significant role.