The price of thoughts? (5)
I believe the answer is:
penny
This clue might be a double definition.
'the price' is the first definition.
The answer and definition can be both related to property as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'of thoughts?' is the second definition.
The definition suggests a singular noun which matches the answer.
Can you help me to learn more?
(Other definitions for penny that I've seen before include "coin, decimal with 1a [NEW]" , "Little bit of 18" , "British coin" , "Small unit of currency" , "Copper coin" .)