Dishevelled hag left in filthy place - hideous (7)
I believe the answer is:
ghastly
'hideous' is the definition.
(I've seen this before)
'dishevelled hag left in filthy place' is the wordplay.
'dishevelled' indicates anagramming the letters.
'left' becomes 'l' (common abbreviation**).
'in' is an insertion indicator.
'filthy place' becomes 'sty' (I've seen this before).
'l' put within 'sty' is 'stly'.
'hag' anagrammed gives 'gha'.
'gha'+'stly'='GHASTLY'
(Other definitions for ghastly that I've seen before include "Cadaverous" , "Hideous" , "Gruesome, repellent" , "Macabre" , "Very pale" .)