Splendid bottle opener. Splendid! (6)
I believe the answer is:
superb
'splendid' is the definition.
(both can mean excellent)
'splendid bottle opener' is the wordplay.
'splendid' becomes 'super' (I've seen this in another clue).
'opener' suggests taking the first letters.
The initial letter of 'bottle' is 'b'.
'super'+'b'='SUPERB'
(Other definitions for superb that I've seen before include "First-class" , "Outstandingly excellent" , "Triumphantly effective" , "Magnificent, quite splendid" , "Dazzling" .)