The most common and most likely answer to this crossword clue is the 9 letter word PESSIMIST
I've seen this crossword clue in The Times
P
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S
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More clues leading to the result PESSIMIST
- I avoid returning during deadly epidemic — it’s not good for me
- Hopeless sort of computer game is included in trial
- One has little hope for “Spies” – terrible film
- Doom merchant Times – piss off!
- One girl about to be grabbed by unwanted person expects the worst
- Nuisance embracing single girl upset killjoy
- Misses tip about cynic
- Cassandra‘s somewhat stuck-up habits – I miss episode
Buddy explains!

The straight part
We know that "it’s not good for me" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case it’s not good for me = pessimist.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 PESSIMIST mean?
PESSIMIST noun- Someone who habitually expects the worst outcome; one who looks on the dark side of things.