Cane, terrible condition (4)
I believe the answer is:
acne
'condition' is the definition.
(acne is a kind of condition)
'cane terrible' is the wordplay.
'terrible' indicates an anagram.
'cane' anagrammed gives 'ACNE'.
(Other definitions for acne that I've seen before include "Adolescent skin disease" , "Spotty complaint" , "sort of disease" , "Skin problem, mainly of teenagers" , "Inflammation of glands in skin" .)