Narrow strait accommodating short haul at sea (6)
I believe the answer is:
strict
'narrow' is the definition.
(I've seen this in another clue)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for strict that I've seen before include "Exacting, unsparing" , "Observing exact rules" , "No-nonsense" , "Harsh and severe" , "Hard" .)