Put down, in slang (3)
I believe the answer is:
dis
'put down in slang' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for dis that I've seen before include "Speak disrespectfully to (colloq.)" , "Show contempt" , "Greek underworld" , "Treat without respect - god of the underworld" , "Prefix denoting the opposite of the base word" .)