What does the cryptic crossword clue "I am dust, having decayed in the ground (7)" mean?

The definition is "ground". The wordplay uses an anagram. anagram of I + AM + DUST, = STADIUM; definition: "ground" The answer is STADIUM.

I am dust, having decayed in the ground (7)

Guardian Cryptic #29048 | 22 Down | 2023-04-19 flower