Fuse, as metal (4)
I believe the answer is:
weld
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">fuse as metal</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for weld that I've seen before include "Join by fusion; dye plant" , "Solder" , "Type of metal joint" , "Lewd (anag.)" , "Join; fuse" .)