Crossword puzzle clue "they're under cities"

They're under cities

It flows under cities

They're hailed in cities everywhere

They may be used to highlight large cities

They're fed in cities

They're seen in many cities at noon

It's classified by the U.S.D.A. as red meat under cooking guidelines and as poultry under inspection standards

"Under capitalism, man exploits man. Under communism, it's ___": John Kenneth Galbraith