From the very beginning, is good at golf (7)
I believe the answer is:
scratch
'golf' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for scratch that I've seen before include "In golf, a handicap of zero strokes" , "handle superficial irritation" , "Score with a sharp point" , "Score a surface" , "Handicap where expected to make" .)