Something hard to value highly? (3)
I believe the answer is:
gem
'value highly?' is the definition.
The answer and definition can be both related to property as well as being singular nouns.
Maybe there's a link between them 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 gem that I've seen before include "A precious stone like a diamond or emerald etc" , "A jewel of an Orangeman" , "Diamond, ruby, or emerald" , "perfect specimen" , "Valuable stone" .)