Garments appear dishevelled on student (7)
I believe the answer is:
apparel
'garments' is the definition.
(thesaurus)
'appear dishevelled on student' is the wordplay.
'dishevelled' indicates anagramming the letters.
'on' says to put letters next to each other.
'student' becomes 'l' (as in L-plates for learner drivers).
'appear' with letters rearranged gives 'appare'.
'appare'+'l'='APPAREL'
(Other definitions for apparel that I've seen before include "what's in the press?" , "Raiment" , "Formal word for clothing" , "Attire" , "whatever people have on" .)