Husband an idiot to mount scrubber (6)
I believe the answer is:
loofah
'scrubber' is the definition.
(something used to scrub one's body)
'husband an idiot to mount' is the wordplay.
'husband' becomes 'h'.
'an' becomes 'a'.
'idiot' becomes 'fool' (both can mean a stupid person).
'to mount' says the letters should be written backwards (letters go up, as in a horse mounting).
'h'+'a'+'fool'='hafool'
'hafool' written backwards gives 'LOOFAH'.
(Other definitions for loofah that I've seen before include "Hard bathroom sponge" , "Bath scrubber" , "Fibre used as a back-scrub" , "Dried gourd pod used as bath sponge" , "Rough sort of sponge" .)