Scratch or nick
I believe the answer is:
flaw
I believe this is a double definition.
'scratch' is the first definition.
(I've seen this in another clue)
'nick' is the second definition.
(thesaurus)
(Other definitions for flaw that I've seen before include "failing" , "Error in theory or plan" , "weak spot" , "(Make) defect(ive)" , "Defect, imperfection" .)