Slight sucking noise curtailed (4)
I believe the answer is:
slur
'slight' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for slur that I've seen before include "Insinuation, allegation" , "Speak disparagingly of - speak indistinctly" , "Slight - incoherence in speech" , "Slight lack of distinction in speech" , "Insinuation; indistinct utterance" .)