Clue: Facial adornment – careless (8)
Answer: SLAPDASH
Explanation: Definition: Facial adornment
Double definition, the first referring to roughcast ( a plaster mixed with stones, used to coat (adorn) the outside walls (faces) of a building. 
Hovis @2 has provided an alternative parsing to this (ie. SLAP ("make-up") + the – in the clue ("dash")