Engineer locates impure, valuable substance (8,5)
I believe the answer is:
precious metal
'valuable substance' 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?
'engineer locates impure' is the wordplay.
'engineer' is an anagram indicator.
'locates'+'impure'='locatesimpure'
'locatesimpure' anagrammed gives 'PRECIOUS METAL'.
Can you help me to learn more?
(Other definitions for precious metal that I've seen before include "no lead!" , "Eg gold, silver or platinum" , "gold, perhaps" , "Platinum, perhaps" .)