Reverse edges of inferior part of spur (5)
I believe the answer is:
rowel
This might be a double definition.
'reverse edges of inferior' is the first definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'part of spur' is the second definition.
(part of a spur used in horse-riding)
(Other definitions for rowel that I've seen before include "Spur's spiked wheel" , "Spiked disc on spur" , "piece on Spurs" , "Goad" , "Spur spikes" .)