Battery end (5)
I believe the answer is:
anode
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">battery end</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 anode that I've seen before include "Positive connection" , "Eg, battery terminal" , "Positive terminal" , "Electrical pole" , "Electrical terminal" .)