A first for this series -- no getting into it halfway through (8)
I believe the answer is:
alphabet
'a first for this series no getting into it halfway through' is the definition.
'alphabet' can be an answer for 'series' (I have seen 'series of letters' mean 'alphabet' so perhaps 'series' could also mean 'alphabet'). I am not sure about the remainder of the definition.
'a first for this series no getting into' is the wordplay.
'a' becomes 'alpha' (the Greek letter A).
'first for' suggests taking the first letters.
'series no' becomes 'be' (I can't explain this - if you can you should believe this answer much more).
'getting into' is an insertion indicator.
The initial letter of 'this' is 't'.
'alpha'+'t'='alphat'
'alphat' placed around 'be' is 'ALPHABET'.
Can you help me to learn more?
(Other definitions for alphabet that I've seen before include "Ordered set of letters" , "Set of letters used in writing" , "lots of characters" , "Confusing assortment of initials" , "Group of characters" .)