Concerned with young woman getting careless (6)
I believe the answer is:
remiss
'careless' is the definition.
(I've seen this before)
'concerned with young woman getting' is the wordplay.
'concerned with' becomes 're' (re can mean regarding, concerning).
'young woman' becomes 'miss' (title for a young woman).
'getting' means one lot of letters go next to another.
're'+'miss'='REMISS'
(Other definitions for remiss that I've seen before include "Derelict in duty" , "delinquent" , "Negligent, lax" , "Neglectful" , "Negligent like misers" .)