The most common and most likely answer to this crossword clue is the 9 letter word COLUMNIST
I've seen this crossword clue in The Times
C
O
L
U
M
N
I
S
T
Buddy explains!

The straight part
We know that "Writer" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case writer = columnist.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does COLUMNIST mean?
COLUMNIST noun- A regular writer of a column, such as in a magazine or newspaper