What Marcie calls Peppermint Patty (3)
I believe the answer is:
sir
'what marcie calls peppermint patty' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sir that I've seen before include "Noble title of undesirable kind" , "Polite term of address for a man" , "Term of address for a gentleman" , "Title of Kt or Bart" , "Way to address gentleman" .)