The most common and most likely answer to this crossword clue is the 7 letter word MELTING
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More clues leading to the result MELTING
Buddy explains!

The straight part
We know that "Crucible" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case crucible = melting.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does MELTING mean?
MELTING verb- To change (or to be changed) from a solid state to a liquid state, usually by a gradual heat.
- To dissolve, disperse, vanish.
- To soften, as by a warming or kindly influence; to relax; to render gentle or susceptible to mild influences; sometimes, in a bad sense, to take away the firmness of; to weaken.
- To be discouraged.
- To be emotionally softened or touched.
- To be very hot and sweat profusely.
- The process of changing the state of a substance from solid to liquid by heating it past its melting point.
- The act of softening or mitigating.
- Which is melting, dissolving or liquefying.
- Given over to strong emotion; tender; aroused; emotional, tearful.
- That causes one to melt with emotion; able to make others feel tender and emotional.