Fail again being careless (6)
I believe the answer is:
remiss
I believe this clue is a double definition.
'fail again' is the first definition.
('miss' is an answer for 'fail' so perhaps 'remiss' is OK for 'fail again')
'careless' is the second definition.
(I've seen this in another clue)
'being' is the link.
(Other definitions for remiss that I've seen before include "Not taking care" , "Failing in one's duty" , "Negligent in performing duties" , "Careless and inattentive" , "Negligent like misers" .)