Perception changed with depressants (5-10)

I believe the answer is:

sharp-wittedness

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'perception' is the definition.
Both the answer and definition are singular nouns.
Perhaps they are linked in a way I don't understand?

'changed with depressants' is the wordplay.
'changed' indicates an anagram.
'with'+'depressants'='withdepressants'
'withdepressants' anagrammed gives 'SHARP-WITTEDNESS'.

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I've seen this clue in the Sydney Morning Herald.

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