Perfidious producer of pork pies (4)
I believe the answer is:
liar
This might be a double definition.
'perfidious producer' is the first definition.
The answer and definition can be both people as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'of pork pies' is the second definition.
The definition suggests a singular noun which matches the answer.
Can you help me to learn more?
(Other definitions for liar that I've seen before include "Teller of untruths" , "Dishonest person" , "Person regularly 'economical with the truth'" , "Person telling stories" , "Bearer of false witness" .)