Rode noisily one way (4)
I believe the answer is:
road
'one way' is the definition.
(I know that road is a type of agency)
'rode noisily' is the wordplay.
'noisily' shows a homophone (sound like).
'rode' sounds like 'ROAD'.
(Other definitions for road that I've seen before include "'The . . . . to hell is paved with good intentions'" , "Thoroughfare" , "Way to achieving a particular outcome" , "See 2" , "Path" .)