What does the cryptic crossword clue "Keep being swept away by the tide, perhaps? (10)" mean?

The definition is "Keep being swept away by the tide, perhaps?". The wordplay uses a cryptic definition. Cryptic definition The answer is SANDCASTLE.

Keep being swept away by the tide, perhaps? (10)

Times Cryptic #28723 | 18 Across | 2023-10-02 flower