Slight legato effect (4)

I believe the answer is:

slur

This clue is a double definition.

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

'legato effect' is the second definition.
(I've seen this in another clue)

(Other definitions for slur that I've seen before include "Stigma" , "Slight, insult" , "Contentious allegation" , "It's not clear, so to speak" , "making indistinct sound" .)

I've seen this clue in The Telegraph and The Globe and Mail.

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