Cowboy boot attachment (4)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
spur
'cowboy boot attachment' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for spur that I've seen before include "Sharp pointed projection" , "Egg on or goad as horseman might" , "Goad; stimulus" , "railway siding" , "Cowboy boot attachment" .)