Melting pot (8)
(Other definitions for cauldron that I've seen before include "A large deep pot for boiling things" , "Very large metal pot for boiling" , "Large kettle" , "Place that's seething" , "Witch's brewing pot" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">melting pot</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for crucible that I've seen before include "smelting vessel" , "Metal-melting container" , "hearth" , "Pot in which metals are melted" , "severe test" .)