Foul zip location (5,3,4)
I believe the answer is:
below the belt
This clue is a double definition.
'foul' is the first definition.
(thesaurus)
'zip location' is the second definition.
(a trouser zip is located below the belt)
(Other definitions for below the belt that I've seen before include "Unfair, disregarding the rules" , "Unfair, cheating" , "Foul landing place for blow" , "position of trousers" , "dirty" .)