Sloppy make-up style (8)
I believe the answer is:
slapdash
'sloppy' is the definition.
(I know that sloppy can be written as slapdash)
'make-up style' is the wordplay.
'make-up' becomes 'slap' (informal term for make-up).
'style' becomes 'dash' (synonyms).
'slap'+'dash'='SLAPDASH'
(Other definitions for slapdash that I've seen before include "In a careless manner" , "Hasty and careless - hit and run?" , "Perfunctory" , "Careless - haphazard" , "Messy" .)