Based on the clue 'a red flag is a sure sign to do this', what is the answer?

Based on the clue 'a rectifier is an electrical device used to conver...', what is the answer? Based on the clue 'a red beverage introduced for public sale bore the...', what is the answer? Based on the clue 'a red c surrounding a yellow ball for gold appears...', what is the answer? Based on the clue 'a red cake named for this smooth fabric is really ...', what is the answer? Based on the clue 'a red giant star has exhausted all of this element...', what is the answer? What is referred to by 'a red hook ladder'? Based on the clue 'a red letter a with a halo', what is the answer? Based on the clue 'a red maple leaf on a white background adorns its ...', what is the answer?