Canal boats (6)
I believe the answer is:
barges
'canal boats' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for barges that I've seen before include "Long boats on inland waterways" , "Canal boats, used to be towed along" , "Longboats on inland waterways" , "Broad flat-bottomed boats" , "Inland waterway boats" .)