Crossword clue: One having an identity crisis?

The answer "SOURCE" fits the clue "One having an identity crisis" because a source can refer to where something comes from or originates. When someone has an identity crisis, they may struggle to understand their true self or where they belong. In this way, they are questioning their own source of identity. Thus, the word cleverly connects the idea of searching for one's true self with the concept of a source.