One reeks dreadfully of paraffin (8)
I believe the answer is:
kerosene
'paraffin' is the definition.
(thesaurus)
'one reeks dreadfully' is the wordplay.
'dreadfully' is an anagram indicator.
'one'+'reeks'='onereeks'
'onereeks' is an anagram of 'KEROSENE'.
'of' is the link.
(Other definitions for kerosene that I've seen before include "No seeker for American fuel oil" , "Sore knee (anag.)" , "Combustible" , "Oil used as fuel in lamps and heaters" , "Paraffin oil (E, not I)" .)