Metal fence (7)
I believe the answer is:
railing
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">metal fence</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 railing that I've seen before include "Barrier of a horizontal bar and supports" , "Complaining bitterly - barrier" , "border of park?" , "Metal barrier" , "Banter" .)