Clothes appear dishevelled by the end of school (7)
I believe the answer is:
apparel
'clothes' is the definition.
(synonyms)
'appear dishevelled by the end of school' is the wordplay.
'dishevelled' indicates an anagram.
'by' is a charade indicator (letters next to each other).
'the end of' suggests the final letters.
The final letter of 'school' is 'l'.
'appear' anagrammed gives 'appare'.
'appare'+'l'='APPAREL'
(Other definitions for apparel that I've seen before include "kit" , "Clothing, things to wear" , "what's in the press?" , "Real pap (anag) - clothing" , "Raiment" .)