What does the cryptic crossword clue "Acknowledgement of success is rare? Certainly not (4,4)" mean?

The wordplay uses a charade (building blocks). WELL (synonym="WELL") + DONE (synonym="DONE") = WELLDONE The answer is WELLDONE.

Acknowledgement of success is rare? Certainly not (4,4)

Guardian Cryptic #29441 | 17 Down | 2024-07-22 flower