The most common and most likely answer to this crossword clue is the 6 plus 7 letter word BECOME ENGAGED
I've seen this crossword clue in The Daily Telegraph
B
E
C
O
M
E
E
N
G
A
G
E
D
Buddy explains!
The straight part
We know that "Get the job/be accepted for a union" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case get the job/be accepted for a union = become engaged.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.