Sort of nail in one's shoe (3)
I believe the answer is:
toe
'nail in one's shoe' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe there's an association between them I don't understand?
'sort of' is the wordplay.
I cannot really see how this works, but
'of' could be 'o' and 'o' is located in the answer.
The remaining letters 'te' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for toe that I've seen before include "A foot division" , "Calabria?" , "Digit; kick" , "End of foot" , "End of sock" .)