Cleaner tackles little boy's chamber (7)
I believe the answer is:
bedroom
'chamber' is the definition.
(I know that chamber can be written as bedroom)
'cleaner tackles little boy's' is the wordplay.
'cleaner' becomes 'broom' (I've seen this before).
'tackles' means one lot of letters goes inside another (tackle can mean to intercept or surround).
'little boy' becomes 'Ed' (nickname or 'little' form of Edward).
'broom' enclosing 'ed' is 'BEDROOM'.
(Other definitions for bedroom that I've seen before include "Sleeping place" , "Chamber of repose" , "Pit" , "Boudoir" , "Boredom (anag)" .)