Such pies can be deceptive (4)
I believe the answer is:
pork
'such pies can' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for pork that I've seen before include "Swine's flesh" , "Pig meat" , "Meat used in sausages" , "what we get from swine" , "Food -- hats -- falsehoods" .)