Astronomer's instrument (9)
I believe the answer is:
telescope
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">astronomer's instrument</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 telescope that I've seen before include "It magnifies the image of distant objects" , "contract" , "Magnifier of distant images" , "Instrument to magnify the image of distant objects" , "Magnifier of distant objects" .)