Ancient stone implement (7)
I believe the answer is:
neolith
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">ancient stone implement</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 neolith that I've seen before include "Prehistoric stone tool - hotline (anag)" , "Ancient stone implement" , "Old stone tool" , "maybe used at Stonehenge?" , "Stone Age artefact" .)