Swamp in which ghouls wander (6)
I believe the answer is:
slough
'swamp' is the definition.
(I know that slough is a type of swamp)
'ghouls wander' is the wordplay.
'wander' indicates an anagram.
'ghouls' with letters rearranged gives 'SLOUGH'.
'in which' is the link.
(Other definitions for slough that I've seen before include "Discard - bog" , "where friendly bombs were wanted" , "Berkshire town and local authority" , "Swamp; Berkshire town" , "Berkshire town - bog - shed" .)