Without vehicle? Without key? That's sloppy! (8)
I believe the answer is:
careless
'sloppy' is the definition.
(synonyms)
'without vehicle? without key?' is the wordplay.
I cannot really see how this works, but
'without' could be 'less' (I've seen this in another clue) and 'less' is found within the answer.
'vehicle?' could be 'car' (car is a kind of vehicle) and 'car' is located in the answer.
'key?' could be 'e' (musical key) and 'e' is found in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for careless that I've seen before include "Negligent, unconcerned" , "Not careful or thorough enough" , "Sloppy" , "Inattentive and negligent" , "Slapdash" .)