The most common and most likely answer to this crossword clue is the 3 letter word IDA
I've seen this crossword clue in The Times
I
D
A
More clues leading to the result IDA
- Papers supplied by a musical princess
- Operatic role thought to release energy
- Princess visiting Trinidad
- Operatic role thought to lack energy
- Girl of 14
- Girl has help cycling
- Princess sounding like a duck
- Girl Friday, no cook
- A challenge for Cretan climbers, they say, getting down from it?
- There’s a princess turning up here
Buddy explains!

The straight part
We know that "Princess" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case princess = ida.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.