The most common and most likely answer to this crossword clue is the 8 letter word MARRIAGE
M
A
R
R
I
A
G
E
More clues leading to the result MARRIAGE
- Guitarist, one with three-note combination
- Union anger over opening of investigation following damage
- Union initially increasing cost of transport tenfold
- Church occasion? A bishop and I may be entertained by ancient priest
- Old lady’s right tantrum taking one in matrimony
- Union put up for instance with broadcast strike
- Crowd’s rising frenzy catching first person in nuptials
- Arrives before one to get into game, rescheduled match
- After strike’s over, see red keeping one in union
- What bridegroom may get me at rip-roaring resorts bordering Oman’s capital
Buddy explains!

The straight part
We know that "Union" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case union = marriage.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 MARRIAGE mean?
MARRIAGE noun- The state of being married.
- A union of two or more people that creates a family tie and carries legal, social, and/or religious rights and responsibilities.
- A homosexual relationship between male prisoners.
- A wedding; a ceremony in which people wed.
- A close union.
- A joining of two parts.
- A king and a queen, when held as a hand in Texas hold 'em or melded in pinochle.
- In solitaire or patience games, the placing a card of the same suit on the next one above or below it in value.