Are no longer first (5)
I believe the answer is:
exist
'are' is the definition.
(I've seen this before)
'no longer first' is the wordplay.
'no longer' becomes 'ex'.
'first' becomes 'ist'.
'ex'+'ist'='EXIST'
(Other definitions for exist that I've seen before include "Be alive" , "Get a life!" , "Live" , "Subsist" , "Scrape by" .)