Show how unused story is no longer fresh (5)
I believe the answer is:
stale
'no longer fresh' is the definition.
(I've seen this in another clue)
'show how unused story' is the wordplay.
'unused' suggests deleting specific letters.
'story' becomes 'tale' (synonyms).
'show' with 'how' taken out is 's'.
's'+'tale'='STALE'
'is' is the link.
(Other definitions for stale that I've seen before include "Lacking freshness" , "past the sell-by date" , "piss" , "Unfresh" , "no longer bearing interest?" .)