Fishy appearance as 'Buffalo Bill' (4)
I believe the answer is:
cody
'buffalo bill' is the definition.
(I've seen this in another clue)
'fishy appearance' is the wordplay.
'fishy' becomes 'cod' (type of fish).
'appearance' becomes 'y' (I am not sure about this - if you are sure you should believe this answer much more).
'cod'+'y'='CODY'
'as' is the link.
Can you help me to learn more?
(Other definitions for cody that I've seen before include "Surname of Buffalo Bill" , "Buffalo Bill's surname" .)