Not considered a disfigurement (4)
I believe the answer is:
rash
'not considered' is the definition.
(thoughtless or not considered properly)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for rash that I've seen before include "Careless" , "spate" , "Unwisely incurring danger" , "(Armed) incursion (into another country)" , "Foolhardy with skin ailment" .)