The most common and most likely answer to this crossword clue is the 9 letter word CONNECTED
C
O
N
N
E
C
T
E
D
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 = connected.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 CONNECTED mean?
CONNECTED verb- (of an object) To join (to another object): to attach, or to be intended to attach or capable of attaching, to another object.
- (of two objects) To join: to attach, or to be intended to attach or capable of attaching, to each other.
- (of an object) To join (two other objects), or to join (one object) to (another object): to be a link between two objects, thereby attaching them to each other.
- (of a person) To join (two other objects), or to join (one object) to (another object): to take one object and attach it to another.
- To join an electrical or telephone line to a circuit or network.
- To associate; to establish a relation between.
- To make a travel connection; to switch from one means of transport to another as part of the same trip.
- (usually with "well-"): Having favorable rapport with a powerful entity.
- Having relationships; involved with others.
- Involved with organized crime, specifically someone not (yet) working for a crime organization, but referred to as a "friend" by made guys/wise guys inside the organization.
- Intimate; Having bonds of affection.
- (of a topological space) That cannot be partitioned into two nonempty open sets.
- (of a graph) Having a path, either directed or undirected, connecting every pair of vertices.
- Having or supporting connections, especially when through technology such as networking software or a transportation network.