The most common and most likely answer to this crossword clue is the 2 letter word SO
S
O
More clues leading to the result SO
Buddy explains!

The straight part
We know that "Indifferent" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case indifferent = so.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 SO mean?
SO adjective- True, accurate.
- In that state or manner; with that attribute. A proadjective that replaces the aforementioned adjective phrase.
- Homosexual.
- To the (explicitly stated) extent that.
- To the (implied) extent.
- In a particular manner.
- In the same manner or to the same extent as aforementioned; also.
- With as To such an extent or degree; as.
- In order that.
- With the result that; for that reason; therefore.
- Provided that; on condition that, as long as.
- Used after a pause for thought to introduce a new topic, question or story.
- Short for so what.
- Used to connect previous conversation or events to the following question.
- Used to introduce a rhetorical question.
- Be as you are; stand still; used especially to cows; also used by sailors.
- Some person.
- A syllable used in solfège to represent the fifth note of a major scale.
- (foods) A type of dairy product, made especially in Japan between the seventh and 10th centuries, by reducing milk by boiling it.