Guide: one goes on foot (7)
I believe the answer is:
trainer
'foot' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'guide one goes' is the wordplay.
'guide' becomes 'train' (I've seen this before).
'one goes' becomes 'er' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'train'+'er'='TRAINER'
'on' acts as a link.
Can you help me to learn more?
(Other definitions for trainer that I've seen before include "Coach - item of footwear" , "Shoe; educator" , "Casual shoe" , "Sports instructor" , "Coach; shoe" .)