Wrong term for a quarter mile! (5)
I believe the answer is:
Here is my best explanation:
'mile' is the definition.
The answer and definition can be both quantities as well as being singular nouns.
Maybe there's an association between them I don't understand?
'wrong term for a quarter' is the wordplay.
'wrong' indicates anagramming the letters.
'for' is a charade indicator (letters next to each other).
'a quarter' becomes 'e'.
'term' anagrammed gives 'metr'.
(Other definitions for metre that I've seen before include "Approx. thirty nine point three seven inches", "39.37 inches", "Distance", "determined by scanning", "Rhythm", "Poetic rhythm", "measure of length", "1.094 yards", "Length unit" and "Approximately 39 inches".)