Weakness makes me tired (7)
I believe the answer is:
demerit
'weakness' is the definition.
The answer and definition can be both human attributes as well as being singular nouns.
Maybe there's an association between them I don't understand?
'makes me tired' is the wordplay.
'makes' indicates anagramming the letters.
'me'+'tired'='metired'
'metired' is an anagram of 'DEMERIT'.
Can you help me to learn more?
(Other definitions for demerit that I've seen before include "Mark given for a fault" , "Something deserving censure" , "Conduct that deserves censure" , "Fault, defect" , "Black mark" .)