What does the cryptic crossword clue "Dirty residence half scrubbed up (4)" mean?

The definition is "Dirty". The wordplay uses a reversal. DWEL (reversal="DWEL") = LEWD; definition: "Dirty" The answer is LEWD.

Dirty residence half scrubbed up (4)

Guardian Cryptic #29271 | 8 Down | 2024-01-05 flower