The most common and most likely answer to this crossword clue is the 5 letter word YOKED
Y
O
K
E
D
More clues leading to the result YOKED
Buddy explains!

The straight part
We know that "joined" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case joined = yoked.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 YOKED mean?
YOKED verb- To link or to join.
- To unite, to connect.
- To enslave; to bring into bondage; to restrain; to confine.
- Wearing a yoke.
- Having large and well-defined muscles particularly at the neck and the trapezii (forming thus the “yoke“).
- Married.