Essentially sour grapes in California over backward quote on LSD (6,4)

I believe the answer is:

acetic acid

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'essentially sour grapes in' is the definition.
The answer and definition can be both substances as well as being singular nouns.
Perhaps they are linked in a way I don't understand?

'california over backward quote on lsd' is the wordplay.
'california' becomes 'ca'.
'over' shows that the letters should be reversed in order.
'backward' says the letters should be written backwards.
'quote on' becomes 'cite' (synonyms. I am not sure about the 'on' bit.).
'lsd' becomes 'acid' (synonyms).
'ca' written backwards gives 'ac'.
'cite' written backwards gives 'etic'.
'ac'+'etic'+'acid'='ACETIC ACID'

Can you help me to learn more?

(Other definitions for acetic acid that I've seen before include "pickling stuff?" , "Component of vinegar" .)

I've seen this clue in The Irish Times.

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