One runs from greatest opponent on record (8)
I believe the answer is:
archival
'greatest opponent on record' is the definition.
Although both the answer and definition are adjectives, I can't understand how they can define each other.
'one runs' is the wordplay.
I cannot really understand how this works, but
'one' could be 'i' (Roman numeral) and 'i' is present in the answer.
'runs' could be 'r' (cricket abbreviation) and 'r' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'from' acts as a link.
Can you help me to learn more?
(Other definitions for archival that I've seen before include "Like recordings" , "Record-keeping" , "records?" , "describing record collection" .)