Cyber criminal (6)
I believe the answer is:
hacker
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">cyber criminal</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for hacker that I've seen before include "Computer thief or axe wielder" , "Modern criminal who breaks into computers" , "Computer expert" , "Modern thief who breaks into computer systems" , "potentially a threat to security" .)