And not out of ignorance (3)
I believe the answer is:
nor
'and not' is the definition.
('nor' means 'and also not')
'out of ignorance' is the wordplay.
'out of' indicates a hidden word.
'NOR' is hidden in the letters of 'ignorance'.
(Other definitions for nor that I've seen before include "Link word" , "Negative conjunction" , "And not; Norman (abbr.)" , "Negative word" , "Neither pairing" .)