Small hourglass (3,5)
I believe the answer is:
egg timer
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">small hourglass</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for egg timer that I've seen before include "One may be set to, say, three minutes" , "Sandglass that runs for three (or four?) minutes" , "device for boiler" , "Meter gig for measuring the boiling of hen-fruit" , "Four-minute hourglass" .)