It's about girl, negligent (6)
I believe the answer is:
remiss
'negligent' is the definition.
(similar in meaning)
'it's about girl' is the wordplay.
'it's about' becomes 're' (regarding).
'girl' becomes 'miss' (term of address for an unmarried woman).
're'+'miss'='REMISS'
(Other definitions for remiss that I've seen before include "delinquent" , "Culpable" , "Neglectful" , "Negligent, derelict" , "Failing in what duty requires" .)