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