Insult indistinctly (4)
I believe the answer is:
slur
'insult' is the definition.
(I've seen this before)
I cannot 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 "Speak as drunk perhaps" , "Pronounce indistinctly or cast abuse on reputation" , "Slight; blur" , "Slight lack of distinction in speech" , "Speak indistinctly, as a drunk might" .)