Cleaner sort of transport for a bad speller? (10)
I believe the answer is:
broomstick
I believe this clue is a double definition.
'cleaner' is the first definition.
(something which cleans)
'sort of transport for a bad speller?' is the second definition.
(transport for a witch, evil person casting spells)
(Other definitions for broomstick that I've seen before include "Handle" , "it has a dreadful woman driver" , "Potters means of transport" , "Something in Harry Potter" , "Potter's equipment" .)