Protractedly taken in about northern form of writing (8)
I believe the answer is:
longhand
'form of writing' is the definition.
'longhand' can be an answer for 'writing' (longhand is a kind of writing). I am unsure of the 'form of' bit.
'protractedly taken in about northern' is the wordplay.
'protractedly' becomes 'long' (I am not sure about this - if you are sure you should believe this answer much more).
'taken in' becomes 'had' (have can mean to trick or take in).
'about' means one lot of letters goes inside another.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'had' placed around 'n' is 'hand'.
'long'+'hand'='LONGHAND'
Can you help me to learn more?
(Other definitions for longhand that I've seen before include "Ordinary writing of manual origin" , "script" , "It's normally written" , "Ordinary writing - not typing or printing" , "Joined-up writing" .)