Source of aid about racetrack (8)
I believe the answer is:
recourse
'racetrack' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'source of aid about' is the wordplay.
I cannot really see how this works, but
an anagram of 'source' is 'ecours' which is present in the answer.
'about' could be 're' ('re' means regarding or about) and 're' is present in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for recourse that I've seen before include "Help; option" , "one looked to for help?" , "Facility" , "Legal right to demand payment" , "A source of help, like resource" .)