Initially achieving this writer's goal (3)
I believe the answer is:
aim
'goal' is the definition.
(aim is a kind of goal)
'initially achieving this writer's' is the wordplay.
'initially' indicates taking the first letters.
'this writer's' becomes 'im' (the person writing the crossword clues).
The initial letter of 'achieving' is 'a'.
'a'+'im'='AIM'
(Other definitions for aim that I've seen before include "Purpose in directing the rifle" , "Ambition or goal" , "Direct, intend" , "intent" , "End" .)