What does the cryptic crossword clue "Unions urgently shut down and end gigs after rioting (7,8)" mean?

The wordplay uses an anagram. anagram of SHUT + DOWN + END + GIGS = SHOTGUNWEDDINGS The answer is SHOTGUNWEDDINGS.

Unions urgently shut down and end gigs after rioting (7,8)

Daily Mail Cryptic #16786 | 7 Down | 2022-03-04 flower