Louisiana waterway (5)
I believe the answer is:
bayou
'louisiana waterway' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for bayou that I've seen before include "sluggish tributary appears" , "marshy water in New Orleans?" , "Swamp in Louisiana etc" , "US marshland" , "Marshy tributary of lake or river - a buoy (anag)" .)