Cleaner has key to chamber (5)
I believe the answer is:
broom
'cleaner' is the definition.
(I've seen this before)
'key to chamber' is the wordplay.
'key' becomes 'b' (eg B major, musical key).
'to chamber' becomes 'room' (I've seen this in another clue).
'b'+'room'='BROOM'
'has' is the link.
(Other definitions for broom that I've seen before include "Shrub and cleaning implement" , "Shrub and cleaning instrument" , "Yellow-flowered shrub" , "Yellow-flowering shrub" , "Sweeper - shrub" .)