Neither out of ignorance (3)
I believe the answer is:
'neither' is the definition.
(I've seen this before)
'out of ignorance' is the wordplay.
'out of' says the answer is hidden in the clue.
'NOR' is hidden in the letters of 'ignorance'.
(Other definitions for nor that I've seen before include "And not; Norman (abbr.)" , "Common conjunction, goes with neither" , "Neither one ... the other" , "logic circuit" , "Negative word" .)