What does the cryptic crossword clue "Mercian king hiding in walled garden (5)" mean?

The definition is "Mercian king". The wordplay uses a hidden word. Hidden in "mercian king hiding in wallED GARden" The answer is EDGAR.

Mercian king hiding in walled garden (5)

Times Cryptic #28760 | 23 Down | 2023-11-14 flower