Crossword Genius

In practice (without public relations) unsuitably sour or vinegary (6)

Ross

I believe the answer is:

acetic

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'vinegary' is the definition.
(I've seen this before)

I don't understand the remainder of the clue.

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(Other definitions for acetic that I've seen before include "Type of acid derived from vinegar" , "Vinegar-like" , "sort of acid" , "Like the acid in vinegar" , "tart" .)

I've seen this clue in the Evening Standard.
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