What does the cryptic crossword clue "Tap spade over ground (9)" mean?

The definition is "Tap". The wordplay uses an anagram. anagram of SPADE + OVER = EAVESDROP; definition: "Tap" The answer is EAVESDROP.

Tap spade over ground (9)

Daily Mail Cryptic #17160 | 4 Down | 2023-08-10 flower