After all, first lady and new tsarina unawed initially by partner (10)
I believe the answer is:
eventually
'after all' is the definition.
(thesaurus)
'first lady and new tsarina unawed initially by partner' is the wordplay.
'first lady' becomes 'eve' (first woman in the Bible).
'and' is a charade indicator (letters next to each other).
'initially' indicates taking the first letters.
'by' says to put letters next to each other.
'partner' becomes 'ally' (an ally is an associate or supporter).
The first letters of 'new tsarina unawed' is 'ntu'.
'eve'+'ntu'+'ally'='EVENTUALLY'
(Other definitions for eventually that I've seen before include "At last" , "In due course" , "Finally" , "In the end" , "sooner or later" .)