A stop sign possibly unobserved (5)
I believe the answer is:
amber
This might be a double definition.
'a stop sign' is the first definition.
Both the definition and answer are adjectives. Maybe you can see a link between them that I can't see?
'unobserved' is the second definition.
Both the definition and answer are adjectives. Maybe they are linked in a way I don't understand?
'possibly' acts as a link.
Can you help me to learn more?
(Other definitions for amber that I've seen before include "Honey-yellow colour" , "Neither red nor green?" , "Traffic light colour" , "Yellow, translucent fossil resin" , "Middle light" .)