Trampled (on) (4)
'trampled on' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for trod that I've seen before include "Walked (on something)" , "Took steps" , "Pressed (something) down with the feet" , "Walked heavily, put foot down" , "Pressed (grapes) by foot" .)
(Other definitions for infringed that I've seen before include "Contravened, the rules say" , "Encroached or trespassed" .)