Symbol or a Greek letter that’s second to last? I don’t know (9)
I believe the answer is:
ignoramus
'last? i don't know' is the definition.
I can't judge whether this definition defines the answer.
'symbol or a greek letter that's second' is the wordplay.
'symbol' becomes 'ign' (I can't justify this - if you can you should believe this answer much more).
'greek letter' becomes 'mu' (letter from the Greek alphabet).
'that's second' becomes 's' (common abbreviation).
'ign'+'or'+'a'+'mu'+'s'='IGNORAMUS'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for ignoramus that I've seen before include "unwitting person" , "One who knows nothing" , "I wouldn't know" , "One is not intelligent" , "A know-nothing" .)