Man on board, cunning, notes English seaport (5,4)

I believe the answer is:

kings lynn

I'm a little stuck... Click here to teach me more about this clue!

But I can't explain it at all! Could you help me understand?

(Other definitions for kings lynn that I've seen before include "Place" , "Norfolk market town" , "English town" , "English port" .)

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.