What does the cryptic crossword clue "Celebrated time of year, so Celt is dancing (8)" mean?

The wordplay uses an anagram. anagram of SO + CELT + IS = SOLSTICE The answer is SOLSTICE.

Celebrated time of year, so Celt is dancing (8)

Independent Cryptic #11974 | 14 Down | 2025-02-24 flower