The most common and most likely answer to this crossword clue is the 13 letter word SELF-EMPLOYED
I've seen this crossword clue in The Guardian
S
E
L
F
-
E
M
P
L
O
Y
E
D
Buddy explains!
The straight part
We know that "Minding your own business" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case minding your own business = self-employed.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 SELF-EMPLOYED mean?
SELF-EMPLOYED adjective- Working for oneself, rather than for an employer.