A second state test (5)
I believe the answer is:
assay
'test' is the definition.
('assay' can be a synonym of 'test')
'a second state' is the wordplay.
'a second' becomes 'as' (I've seen this in other clues).
'state' becomes 'say' ('say' can be a synonym of 'state'**).
'as'+'say'='ASSAY'
(Other definitions for assay that I've seen before include "Check (a metal's) quality" , "Analyse ore for metal content" , "metallurgical test" , "Test metal for quality" , "Test ore for content" .)