Required north-east editor (twice!) (6)
I believe the answer is:
needed
'required' is the definition.
(I know that required can be written as needed)
'north-east editor twice' is the wordplay.
'north east' becomes 'ne'.
'editor' becomes 'ed' (abbreviation).
'twice' indicates the doubling of some letters.
'ed' doubled is 'eded'.
'ne'+'eded'='NEEDED'
(Other definitions for needed that I've seen before include "'Lacked, required (6)'" , "Required something essential" , "Obligatory" , "Required; sounds like worked (dough)" , "Lacked something essential" .)