Indistinctly make an insult (4)
I believe the answer is:
slur
'insult' is the definition.
(I've seen this before)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for slur that I've seen before include "Slight - smear" , "Speak as drunk perhaps" , "Slight sound" , "Disparage" , "Slight - mumble" .)