Hi-vis strip left in unfinished canteen (9)
I believe the answer is:
reflector
'unfinished canteen' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe there's an association between them I don't understand?
'hi-vis strip left' is the wordplay.
'hi-vis' becomes 'reflect' (I can't explain this - if you can you should give a lot more credence to this answer).
'strip' indicates the central letters (I've seen 'stripping' mean this).
'left' becomes 'port' (left side of a ship - opposite of starboard).
The centre of 'port' is 'or'.
'reflect'+'or'='REFLECTOR'
'in' is the link.
Can you help me to learn more?
(Other definitions for reflector that I've seen before include "Eg, cat's eye" , "telescope" , "Mirror (not a good one?)" , "Newton saw through this" , "One thinking" .)