Covered by maid, ledge gathering dust (4)
I believe the answer is:
idle
'gathering dust' is the definition.
(something gathering dust is idle or unused)
'covered by maid ledge' is the wordplay.
'covered by' indicates a hidden word.
'IDLE' is hidden within 'maid ledge'.
(Other definitions for idle that I've seen before include "Circus entertainer" , "Loaf" , "Empty" , "Useless" , "Fruitless" .)