The most common and most likely answer to this crossword clue is the 9 letter word PROOFREAD
I've seen this crossword clue in The Sunday Telegraph
P
R
O
O
F
R
E
A
D
Buddy explains!
The straight part
We know that "Check writing as academic, pocketing zero cash, mostly" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case check writing as academic, pocketing zero cash, mostly = proofread.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 PROOFREAD mean?
PROOFREAD verb- To check a written text for errors in spelling and grammar.