Bishop fell over brush (5)
I believe the answer is:
broom
'brush' is the definition.
(thesaurus)
'bishop fell over' is the wordplay.
'bishop' becomes 'b' (abbreviation used in chess).
'fell' becomes 'moor' (I've seen this before).
'over' says the letters should be written in reverse.
'moor' written backwards gives 'room'.
'b'+'room'='BROOM'
(Other definitions for broom that I've seen before include "Shrub or sweeping brush" , "Leguminous shrub" , "Long-handled brush" , "Sweeper - shrub" , "Plant - sweeper" .)