Timber used by one (5)
I believe the answer is:
ebony
'timber' is the definition.
The answer and definition can be both human attributes as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
'used by one' is the wordplay.
'used' indicates an anagram.
'by'+'one'='byone'
'byone' with letters rearranged gives 'EBONY'.
Can you help me to learn more?
(Other definitions for ebony that I've seen before include "Hard wood used for black piano keys and in cabinetwork" , "Tree having black wood" , "Hard dark-coloured wood" , "Dark hardwood" , "Very dark black" .)