Slight baseless revision of regulations (4)

I believe the answer is:

slur

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

I don't understand the remainder of the clue.

(Other definitions for slur that I've seen before include "Pronounce indistinctly - discredit" , "Slight - drawl" , "Slight sound" , "Speak as drunk perhaps" , "Slight - incoherence in speech" .)

I've seen this clue in The Hindu.

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