What does the cryptic crossword clue "Treat us with a compound soak (8)" mean?

The definition is "soak". The wordplay uses an anagram. anagram of TREAT + US + A = SATURATE; definition: "soak" The answer is SATURATE.

Treat us with a compound soak (8)

Guardian Cryptic #24406 | 19 Down | 2008-06-04 flower