Slipshod; unthinking (8)
I believe the answer is:
careless
This clue is a double definition.
'slipshod' is the first definition.
(similar in meaning)
'unthinking' is the second definition.
(I've seen this before)
(Other definitions for careless that I've seen before include "Negligent - nonchalant" , "Inattentive - nonchalant" , "Negligent, unconcerned" , "Marked by lack of attention" , "Incautious" .)