Resistance group to the east of a certain county (8)
I believe the answer is:
somerset
'county' is the definition.
(English county)
'resistance group to the east of a certain' is the wordplay.
'resistance' becomes 'r' (electronics abbreviation).
'group' becomes 'set' (both can mean a collection).
'to the east of' means one lot of letters go next to another (some letters go to the right of others).
'a certain' becomes 'some' (eg some person means a certain person).
'r'+'set'='rset'
'rset' put after 'some' is 'SOMERSET'.
(Other definitions for somerset that I've seen before include "part of the west" , "County; acrobat move" , "western county" , "Part of UK" , "Rome sets up in this English county" .)