I lament about disorder (7)
I believe the answer is:
ailment
'disorder' is the definition.
(I know that disorder can be written as ailment)
'i lament about' is the wordplay.
'about' indicates anagramming the letters.
'i'+'lament'='ilament'
'ilament' is an anagram of 'AILMENT'.
(Other definitions for ailment that I've seen before include "infirmity" , "Tummy upset, for instance" , "Physical disorder" , "I lament (anag.)" , "problem" .)