Poor tart eaten by the contrite (6,3)
I believe the answer is:
humble pie
'poor tart' is the definition.
The definition suggests a singular noun which matches the answer.
'eaten by the contrite' is the wordplay.
'eaten by' indicates the central letters (the letters consumed or eaten by the word).
'contrite' becomes 'umblepie' (I can't explain this - if you can you should believe this answer much more).
The centre of 'the' is 'h'.
'h'+'umblepie'='HUMBLE PIE'
Can you help me to learn more?
(Other definitions for humble pie that I've seen before include "What one eats when accepting humiliation" , "To eat this is to apologise" , "It's eaten in humiliation" , "The dish to eat by way of an apology" , "Food of the repentant?" .)