What does the cryptic crossword clue "Nothing doing! (Tricky Dick) (5)" mean?

The definition is "Nothing". The wordplay uses a charade (building blocks). NIX (synonym="NIX") + ON (synonym="ON") = NIXON The answer is NIXON.

Nothing doing! (Tricky Dick) (5)

Times Cryptic #28978 | 21 Down | 2024-07-25 flower