Whitewater transport (4)
I believe the answer is:
raft
'whitewater transport' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for raft that I've seen before include "Floating log structure; large amount" , "... Lots" , "Travel on river, in a way" , "Floating framework" , "Buoyant platform" .)