The term 'Oklahoma! Song Subject' can be solved by the six-letter word 'Surrey'. The song 'Oklahoma!' is from the musical of the same name, which was written by Richard Rodgers and Oscar Hammerstein II. It is set in the Oklahoma Territory in 1906 and tells the story of a farm girl and two cowboys who compete for her affection. The song 'Surrey with the Fringe on Top' is featured in the musical and is sung by the character Curly McLain. The song is about how he and his love, Laurey, will ride in a surrey to their wedding.