What does the cryptic crossword clue "Trouble afoot, bishop going AWOL for wedding (5)" mean?

The definition is "wedding". The wordplay uses a deletion. UNION (deletion) = UNION; definition: "Trouble afoot," The answer is UNION.

Trouble afoot, bishop going AWOL for wedding (5)

Guardian Cryptic #29417 | 8 Across | 2024-06-24 flower