Receiving wallop, ignores a slur in prison (7)
I believe the answer is:
slammer
'prison' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for slammer that I've seen before include "Prison (colloq.)" , "one leaping into crowd" , "Stir" , "Pickwickian doctor" , "Prison (slang)" .)