red

See:

a red cent a red eye a red herring a red-letter day be in the red be like a red rag to a bull be on full alert catch red-handed caught in the act cut through red tape down the little red lane

give a red face go beet red go beetroot in the red not worth a dime one's ears are red out of the red paint the town red red as a cherry red eye red herring

red in the face red ink red tape red-blooded red-carpet treatment red-hot red-letter day roll out the red carpet run a red light see red the red-light district