Freeholder in the old sultanate (6)
I believe the answer is:
yeoman
'freeholder' is the definition.
(yeoman is a kind of freeholder)
'the old sultanate' is the wordplay.
'the old' becomes 'ye' (resembles a historical spelling of 'the').
'sultanate' becomes 'oman' (I've seen this before).
'ye'+'oman'='YEOMAN'
'in' acts as a link.
(Other definitions for yeoman that I've seen before include "... of the Guard (Gilbert and Sullivan)" , "Old English soldier or small farmer" , "Old landholder; member of The Guard" , "Significant sort of service" , "Royal attendant" .)