Restructured eastern firm (7)
I believe the answer is:
earnest
'firm' is the definition.
(I've seen this before)
'restructured eastern' is the wordplay.
'restructured' indicates anagramming the letters (I've seen 'restructuring' mean this).
'eastern' anagrammed gives 'EARNEST'.
(Other definitions for earnest that I've seen before include "Sincere in intention" , "Solemn; pledge" , "serious attention" , "Sincere or over-serious" , "Sincere, solemn" .)