A ripper finally, at the end Don goes; out for a duck (9)
I believe the answer is:
goosander
'a duck' is the definition.
(goosander is a kind of duck)
'a ripper finally at the end don goes out' is the wordplay.
'finally' suggests the final letters.
'at the end' is a charade indicator (letters next to each other).
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
The final letter of 'ripper' is 'r'.
'a'+'r'+'don'+'goes'='ardongoes'
'ardongoes' is an anagram of 'GOOSANDER'.
'for' is the link.
(Other definitions for goosander that I've seen before include "Bird" , "duck" , "Waterbird" .)