Weathercock (4)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">weathercock</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for vane that I've seen before include "Wind pointer" , "Part of a weathercock" , "Device that rotates to show the direction of the wind" , "Blade of windmill" , "Turbine blade" .)