Possibly lower down at heel (5)
I believe the answer is:
rowel
'down at heel' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'possibly lower' is the wordplay.
'possibly' indicates anagramming the letters.
'lower' is an anagram of 'ROWEL'.
Can you help me to learn more?
(Other definitions for rowel that I've seen before include "Spur's spiked wheel" , "Spur spike" , "Part of a spur" , "Spiked disc on spur" , "Spiked wheel on spur" .)