DIY nut is disorganised and messy (6)
I believe the answer is:
untidy
'messy' is the definition.
('untidy' can be a synonym of 'messy')
'diy nut is disorganised' is the wordplay.
'is disorganised' indicates anagramming the letters.
'diy'+'nut'='diynut'
'diynut' with letters rearranged gives 'UNTIDY'.
'and' acts as a link.
(Other definitions for untidy that I've seen before include "Far from neat" , "in a state" , "Not inclined to be neat" , "Not neatly arranged" , "Cluttered" .)