If a noun is listed as separate words, then it stays separate words — and is not hyphenated — as a direct (right in front of the noun) adjective.
…He is in real estate.
…He is a real estate broker.
…He is in high school.
…He is a high school senior.
This gets a little crazy since it means that words need to be looked up even more frequently.
…Odds and ends are being taken care of.
…It is an odds and ends job.