The French cabaret singer referred to in the crossword solution is Edith Piaf, a legendary French singer and cultural icon. She was known for her powerful voice and emotional ballads, which made her one of the most popular performers in France during the mid-20th century. Piaf's songs often reflected her difficult life, including her poverty-stricken childhood and her struggles with addiction. Her music continues to be popular today, and she is remembered as one of the greatest French singers of all time.