Nuclear generator (7)
I believe the answer is:
reactor
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">nuclear generator</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for reactor that I've seen before include "Nuclear installation" , "Apparatus for production of nuclear energy" , "Device to produce energy by nuclear fission" , "one hosting moderator?" , "Nuclear power plant" .)