The particular brush has its own name, the shoebrush or shoe-brush, but dictionaries cannot agree, even with themselves, on which form is proper. It would be prudent to just use the two word form.
(our spell-checker doesn't like either one)
Before 'running shoes' were so popular, shoes were mostly made of leather. They needed to be cleaned with shoe brushes, often 3 of them, one to brush off mud etc, one to apply polish and one to shine the polish. A dying tradition, but I, for one, refuse to wear 'running shoes' for regular attire.
It is one word.
Its one word
One, it's a compound word.
It is one word.
one word
It is one word
Schoolchildren, one word.
One word. 'Sandstorm.'
Yes, daylight is one word!
"Doorway" is one word.
It is one word.