Post Office board member, gutless, told sanctimonious untruth (4,3)
I believe the answer is:
pork pie
'post office board' is the definition.
The definition and answer can be both things that one consumes for nourishment as well as being singular nouns.
Maybe you can see an association between them that I can't see?
'member gutless told sanctimonious untruth' is the wordplay.
I cannot really understand how this works, but
'sanctimonious' could be 'pi' (old-fashioned term for pious) and 'pi' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for pork pie that I've seen before include "One going to the head" , "A butcher supplies this" , "Meat product" , "A fib, some say" , "Lie (rhyming slang)" .)