Deception, of course, is fishy (3)
I believe the answer is:
cod
This could be a double definition.
'deception of course' is the first definition.
The answer and definition can be both things that one consumes for nourishment as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'fishy' is the second definition.
Both the answer and definition are adjectives. Perhaps they are linked in a way I don't understand?
'is' acts as a link.
Can you help me to learn more?
(Other definitions for cod that I've seen before include "Large sea fish- it's a sham" , "method of payment" , "Cash on delivery, in short, for this fish" , "Not a real" , "Fish; fake (colloq.)" .)