Uneducated, unhealthy repeat (10)
I believe the answer is:
illiterate
'uneducated' is the definition.
(associated in meaning)
'unhealthy repeat' is the wordplay.
'unhealthy' becomes 'i'll' (associated in meaning).
'repeat' becomes 'iterate' (synonyms).
'ill'+'iterate'='ILLITERATE'
(Other definitions for illiterate that I've seen before include "Ignorant" , "dunce" , "Wordless" , "Undereducated" , "one who can't read" .)