Disco pulser (6)
I believe the answer is:
strobe
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">disco pulser</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for strobe that I've seen before include "Flashing-light device" , "Flashy type" , "Flashing disco light" , "Protestant reformer" , "Flasher" .)