Electing to omit one somehow seen as carelessness? (7)
I believe the answer is:
neglect
'carelessness?' is the definition.
(I know that carelessness can be written as neglect)
'electing to omit one somehow' is the wordplay.
'to omit' indicates named letters should be taken away.
'one' becomes 'i' (Roman numeral).
'somehow' indicates an anagram.
'electing' with 'i' taken out is 'electng'.
'electng' with letters rearranged gives 'NEGLECT'.
'seen as' is the link.
(Other definitions for neglect that I've seen before include "Fail to look after (something)" , "Not caring" , "Fail to give attention to" , "Omit by carelessness" , "Leave undealt with" .)