Certain hacker

The answer to the crossword question “Certain hacker is AXE” is likely to be the word ANONYMOUS. This likely refers to the online activist/hacker group who are known for their use of the Guy Fawkes mask and the slogan “We are Anonymous.” The word AXE may be a reference to their use of hacking as a tool for social or political change, in essence, “axing” or dismantling the systems they seek to challenge. Overall, the answer references a certain type of hacker – one who operates anonymously and seeks to effect change in society.