Messy bed vacated, case dismissed (7)
I believe the answer is:
unkempt
'messy' is the definition.
(thesaurus)
I don't understand the remainder of the clue.
(Other definitions for unkempt that I've seen before include "Looking untidy or neglected" , "Tangled and untidy, as hair may be" , "in a mess" , "Untidy, dishevelled" , "(Of hair) needing a comb?" .)