Second story is insipid (5)
I believe the answer is:
stale
'insipid' is the definition.
(thesaurus)
'second story' is the wordplay.
'second' becomes 's' (common abbreviation).
'story' becomes 'tale' ('tale' can be a synonym of 'story').
's'+'tale'='STALE'
'is' is the link.
(Other definitions for stale that I've seen before include "past the sell-by date" , "Musty - out of date" , "Least (anag.)" , "Mouldy or hackneyed" , "Old; musty" .)