Each pair of definitions is for two words, where the second word is the first word with a letter deleted (example: brand & band). The length of the first word in each pair is provided, along with the position of the deleted letter to obtain the second word.
1) a pale blue gas and unstable form of oxygen (5 letters) & (delete 1st letter) a section of a city restricted by law for a specific use
2) a type or class, as of literature or music (5 letters) & (delete 4th letter) a hereditary unit on a chromosome
3) to mark with a hot iron (5 letters) & (delete 5th letter) the outer layers of grain
4) a protector or champion of the people (7 letters) & (delete 4th letter) being three in one