The most common and most likely answer to this crossword clue is the 6 letter word SOLDER
I've seen this crossword clue in The Guardian
S
O
L
D
E
R
More clues leading to the result SOLDER
Buddy explains!
The straight part
We know that "Join" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case join = solder.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 SOLDER mean?
SOLDER noun- Any of various easily-melted alloys, commonly of tin and lead, that are used to mend, coat, or join metal objects, usually small.
- Figuratively, circumstances or emotions that strongly bond things or persons together in analogy to solder that joins metals.
- To join items together, or to coat them with solder
- To join things as if with solder.