Prior in favour of me and king (6)
I believe the answer is:
former
'prior' is the definition.
(thesaurus)
'in favour of me and king' is the wordplay.
'in favour of' becomes 'for' (I've seen this before).
'and' is a charade indicator (letters next to each other).
'king' becomes 'r' (r is abbreviation for rex).
'for'+'me'+'r'='FORMER'
(Other definitions for former that I've seen before include "Old < prior < departed" , "not present" , "long ago" , "The first mention of the two" , "The first of two mentioned" .)