Flaw, imperfection (6)
I believe the answer is:
defect
I believe this is a double definition.
'flaw' is the first definition.
(I know that flaw can be written as defect)
'imperfection' is the second definition.
(I know that defect is a type of imperfection)
(Other definitions for defect that I've seen before include "weakness" , "Shortcoming" , "Deficiency" , "Fault, flaw" , "Desert - flaw" .)