One more than an eagle (6)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
birdie
(Other definitions for birdie that I've seen before include "One under par - watch it!" , "Golfing score better than par" , "Good hole" , "In golf, a score of one under par for the hole" , "One under in 20 across" .)