Rock concert equipment (4)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">rock concert equipment</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for amps that I've seen before include "'Units of electric current, in short (4)'" , "Units of electrical power" , "Spam (anag)" , "Current measures" , "Basic units of electric current" .)