Is there a pin-hole in it? (5)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
green
But I can't explain it at all! Could you help me understand?
(Other definitions for green that I've seen before include "Politician; fresh" , "Environmentally sound" , ""Go" signal" , "Environmental - colour" , "Eco-friendly" .)