Driver's aid (6)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">driver's aid</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 satnav that I've seen before include "Driver's route finder" , "course-finding apparatus" , "Electronic direction finder" , "Route guide" , "Driver's guide" .)
(Other definitions for sat nav that I've seen before include "Guidance system" , "Direction-finding equipment" , "Aid" .)