The most common and most likely answer to this crossword clue is the 6 plus 8 letter word PLEASE YOURSELF
I've seen this crossword clue in Financial Times
P
L
E
A
S
E
Y
O
U
R
S
E
L
F
More clues leading to the result PLEASE YOURSELF
Buddy explains!
The straight part
We know that "I don’t care" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case i don’t care = please yourself.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.