Vessel in harbour, almost one that could be mistaken for another (9)
I believe the answer is:
porringer
'vessel in harbour almost one that could be mistaken for another' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'vessel in' is the wordplay.
I cannot quite understand how this works, but
'in' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for porringer that I've seen before include "soup-bowl" , "Soup bowl with handle" , "Small dish" .)