First-class block each, up in a part of Greece (7)

'a part of greece' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.

'first-class block each up' is the wordplay.
'first class' becomes 'ai' (Al - top quality).
'block' becomes 'lot' (I can't justify this - if you can you should believe this answer much more).
'each' becomes 'ea' (abbreviation).
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'ai'+'lot'+'ea'='ailotea'
'ailotea' back-to-front is 'AETOLIA'.

'in' acts as a link.

Can you help me to learn more?