I'm tempted to say that the high point of the Circa '21 Dinner Playhouse's Oklahoma! comes in the show's first minute, when Adam Clough's Curly enters singing "Oh, What a Beautiful Mornin'" in a thrillingly rich, powerful baritone. Such a statement, however, might indicate that the rest of the actor's performance is somehow less of a thrill. Put simply - and with no disrespect meant to director Jay Berkow or the show's other participants - this Oklahoma! works because of Clough.