Fearless, I unwisely printed (8)
I believe the answer is:
intrepid
'fearless' is the definition.
('intrepid' can be a synonym of 'fearless')
'i unwisely printed' is the wordplay.
'unwisely' is an anagram indicator.
'printed' anagrammed gives 'ntrepid'.
'i'+'ntrepid'='INTREPID'
(Other definitions for intrepid that I've seen before include "stout" , "'Brave, dauntless (8)'" , "Bold" , "Fearlessly adventurous" , "Undaunted" .)