Unit of magnetic field strength (7)
I believe the answer is:
oersted
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">unit of magnetic field strength</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 oersted that I've seen before include "Physics unit of magnetic field strength" , "Ted Rose (anag) - Danish physicist who discovered electromagnetism" , "Physical unit" .)