Door rivet (8)
I believe the answer is:
entrance
This clue could be a double definition.
'door' is the first definition.
(I've seen this before)
'rivet' is the second definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe there's an association between them I don't understand?
Can you help me to learn more?
(Other definitions for entrance that I've seen before include "Enrapture; door" , "Way in - hypnotise" , "it's common, say, for some children to sit" , "Way in - bewitch" , "Carry away" .)