The most common and most likely answer to this crossword clue is the 9 letter word IGNORAMUS
I've seen this crossword clue in The Times
I
G
N
O
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A
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More clues leading to the result IGNORAMUS
- Amusing or silly fool
- Fool not wholly benign or amusing
- Stupid person or amusing eccentric?
- Fool is amusing or funny
- Dimwit’s problem a boy soldier reversed
- Yours truly's taking in good female American who needs education
- Lunatic or amusing fool?
- Outsmarting drunk, TT's left one in a state of bliss?
- Dummy run in a mo, using bombing
- . Idiot to neglect contract, a total set-up
Buddy explains!

The straight part
We know that "one in a state of bliss" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one in a state of bliss = ignoramus.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 IGNORAMUS mean?
IGNORAMUS noun- A totally ignorant person—unknowledgeable, uneducated, or uninformed; a fool.
- A grand jury's ruling on an indictment when the evidence is determined to be insufficient to send the case to trial.