Think again since order re-established (10)
I believe the answer is:
reconsider
'think again' is the definition.
('consider' is an answer for 'think' so perhaps 'reconsider' is OK for 'think again')
'since order re-established' is the wordplay.
're-established' indicates an anagram.
'since'+'order'='sinceorder'
'sinceorder' is an anagram of 'RECONSIDER'.
(Other definitions for reconsider that I've seen before include "Ponder further" , "Have second thoughts" , "Think again" , "Nice orders ( anag.)" .)