Ruled fad out that's awesome (8)
I believe the answer is:
dreadful
'awesome' is the definition.
(thesaurus)
'ruled fad out' is the wordplay.
'out' is an anagram indicator (out can mean wrong or inaccurate).
'ruled'+'fad'='ruledfad'
'ruledfad' anagrammed gives 'DREADFUL'.
'that's' acts as a link.
(Other definitions for dreadful that I've seen before include "Shockingly bad" , "Horrible, shocking" , "Informally very bad, perhaps the weather" , "Appalling, awful" , "Extremely bad or disagreeable" .)