The most common and most likely answer to this crossword clue is the 3 letter word EGO
I've seen this crossword clue in The Times
E
G
O
More clues leading to the result EGO
- Morale, say, on first of ops
- I turn on stove in the end
- Scapegoat retaining such personal pride
- I say you must lose the jacket
- I make good, to some extent
- I pass after end of course
- English travel showing self-importance
- I must display energy in different ways
- Self-importance displayed by the gods
- Self-esteem to depart after low grade
Buddy explains!

The straight part
We know that "I" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case i = ego.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 EGO mean?
EGO noun- The self, especially with a sense of self-importance.
- (Freudian) The most central part of the mind, which mediates with one's surroundings.