Expertise shown by exquisite society in the Home Counties (7)
I believe the answer is:
finesse
'expertise' is the definition.
(thesaurus)
'exquisite society in the home counties' is the wordplay.
'exquisite' becomes 'fine' ('fine' can be a synonym of 'exquisite').
'society' becomes 's' (common abbreviation in names of organisations).
'in the' means one lot of letters goes inside another.
'home counties' becomes 'se'.
's' inserted within 'se' is 'sse'.
'fine'+'sse'='FINESSE'
'shown by' acts as a link.
(Other definitions for finesse that I've seen before include "Subtlety in handling difficult situations" , "Subtle skill; bridge ploy" , "Skilful elegance or expertise" , "Subtlety and tact" , "Subtly skilful handling of a situation" .)