What does the cryptic crossword clue "USA proven to distress star having a meltdown (9)" mean?

The wordplay uses an anagram. anagram of USA (synonym="USA") + PROVEN (synonym="PROVEN") = SUPERNOVA The answer is SUPERNOVA.

USA proven to distress star having a meltdown (9)

Guardian Cryptic #29258 | 21 Across | 2023-12-20 flower