Deceive a fish? (3)
I believe the answer is:
cod
I believe this clue is a double definition.
'deceive' is the first definition.
(codding is a kind of deceiving)
'a fish?' is the second definition.
(type of fish)
(Other definitions for cod that I've seen before include "A fish; a hoax, parody" , "swimmer" , "faked" , "Hoax (sl.); fish" , "North Atlantic fish" .)