Retired person returning has to go over the same ground (7)
I believe the answer is:
retread
'retired person' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'returning has to go over the same ground' is the wordplay.
I cannot quite understand how this works, but
'go' could be 'tread' (treading is a kind of going) and 'tread' is present in the answer.
'over' could be 're' and 're' is found within the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for retread that I've seen before include "Remould" , "Second-hand tyre" , "recycled material" , "One much improved in rubber" , "Go back over (one's route) - mend(ed) tyre" .)