A knotty problem for the ship's navigator (4)
I believe the answer is:
reef
This clue might be a double definition.
'a knotty problem' is the first definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'ship's navigator' is the second definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'for the' is the link.
Can you help me to learn more?
(Other definitions for reef that I've seen before include "offshore bank" , "Submerged barrier" , "Underwater obstruction" , "Rocks in shallow water - kind of knot" , "Rock near water's surface" .)