Hat Norma ruined in race (8)
I believe the answer is:
marathon
'race' is the definition.
(thesaurus)
'hat norma ruined' is the wordplay.
'ruined' is an anagram indicator.
'hat'+'norma'='hatnorma'
'hatnorma' anagrammed gives 'MARATHON'.
'in' acts as a link.
(Other definitions for marathon that I've seen before include "Pheidippides' starting point" , "no easy task" , "The longest foot-race" , "Footrace of 26 miles 385 yards" , "26-mile foot race" .)