Symbol of humiliation that could make me, Phi, blue (6,3)
I believe the answer is:
humble pie
'symbol of humiliation that' is the definition.
The definition suggests a singular noun which matches the answer.
'make me phi blue' is the wordplay.
'make' indicates an anagram.
'me'+'phi'+'blue'='mephiblue'
'mephiblue' is an anagram of 'HUMBLE PIE'.
'could' is the link.
Can you help me to learn more?
(Other definitions for humble pie that I've seen before include "Eat this dish to be apologetic" , "It's eaten in humiliation" , "Food of the repentant?" , "The dish to eat by way of an apology" , "It's eaten in abject apology" .)