What does "no clue" mean?

Response affirming that the speaker does not have knowledge pertaining to an interlocutor's question

No clue

Common synonyms include: absence of data, absence of evidence, completely clueless, ignorance, lack of clues, lack of information.

intj

intj ·Rare ·Advanced level

Intj

1
Response affirming that the speaker does not have knowledge pertaining to an interlocutor's question
"Do you know what the weather will be like today? / No clue. Why do you ask?"

"Do you know what the weather will be like today? / No clue. Why do you ask?"

From no + clue, as the speaker does not have a clue about the answer to the question. Most likely a shortened form of "I have no clue".