The tales about distance producing complaint (8,4)
I believe the answer is:
athletes foot
'complaint' is the definition.
(medical complaint)
'the tales about distance' is the wordplay.
'about' indicates anagramming the letters.
'distance' becomes 'foot' (I have seen 'Imperial distance' mean 'foot' so perhaps 'distance' could also mean 'foot').
'the'+'tales'='thetales'
'thetales' is an anagram of 'athletes'.
'athletes'+'foot'='ATHLETES FOOT'
'producing' acts as a link.
(Other definitions for athletes foot that I've seen before include "common complaint with trilbies" , "complaint to do with plates" , "Infection around toes" , "Fungal infection often between toes" .)