Excellent, first-class (8)
I believe the answer is:
splendid
This clue is a double definition.
'excellent' is the first definition.
(I know that excellent can be written as splendid)
'first-class' is the second definition.
(I've seen this before)
(Other definitions for splendid that I've seen before include "Excellent, magnificent" , "'Excellent, glorious (8)'" , "Excellent, first-class" , "Very fine, glorious" , "Magnificent, very impressive" .)