Go against currency jump (4)
I believe the answer is:
buck
I believe this clue is a triple definition!
'go against' is the first definition.
(synonyms)
'currency' is the second definition.
(buck is a kind of currency)
'jump' is the third definition.
(thesaurus)
(Other definitions for buck that I've seen before include "Jump - dollar - male deer" , "A slangy American dollar, may be fast" , "Dandy" , "Male animal - dollar" , "Antelope - dollar" .)