Narrow waterways (7)
I believe the answer is:
straits
'narrow waterways' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for straits that I've seen before include "Sea passages" , "Difficulties" , "... of Magellan, Hormuz" , "Dire --, rock band" , "Narrow channels of the sea joining two larger bodies of water" .)