Tale of Troy's ruin (5)
I believe the answer is:
'tale' is the definition.
'troy's ruin' is the wordplay.
'ruin' indicates anagramming the letters.
'troys' is an anagram of 'STORY'.
'of' acts as a link.
(Other definitions for story that I've seen before include "Account, tale" , "See 10 and 19" , "Rumour" , "Narration" , "Narrative or account" .)