Oregon city on the Willamette (6)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
eugene
(Other definitions for eugene that I've seen before include "opera, but only first half" , ". . . . . . Onegin (Tchaikovsky) (6)" , "Great American playwright . . . . . . O'Neill" , "fellow" , "- - Onedin" .)