The most common and most likely answer to this crossword clue is the 6 letter word WEDDED
I've seen this crossword clue in The Daily Telegraph
W
E
D
D
E
D
More clues leading to the result WEDDED
- Drip plugged by daughters with wife
- Married by eminent cleric in Charlock?
- Joined a day late? No answer
- Wimp keeping theologian in union
- United, we’d daughters bringing in core needs
- Joined in marriage by clergyman in little dilemma at first
- Married English priest in the middle of the week, perhaps
- As is woman with Man United?
Buddy explains!

The straight part
We know that "in union" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case in union = wedded.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 WEDDED mean?
WEDDED verb- To perform the marriage ceremony for; to join in matrimony.
- To take as one's spouse.
- To take a spouse.
- To join or commit to, more or less permanently, as if in marriage.
- To take to oneself and support; to espouse.
- To wager, stake, bet, place a bet, make a wager.
- (of a couple) Joined in marriage.
- Joined as if in a marriage.