May have a pin in it, of course (4)
I believe the answer is:
hole
'course' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for hole that I've seen before include "Awkward situation" , "pocket" , "Opening on golf course" , "Nasty place" , "Gap; difficult situation" .)