Not what one expects from a good writer (6)
I believe the answer is:
scrawl
'writer' is the definition.
Although both the answer and definition are singular nouns, I cannot 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 scrawl that I've seen before include "Write clumsily, hardly legible" , "Illegible hand" , "Untidy writing" , "Hurried writing" , "Write illegibly" .)