Fan giving county mostly support (7)
I believe the answer is:
devotee
'fan' is the definition.
('devotee' can be a synonym of 'fan')
'county mostly support' is the wordplay.
'county' becomes 'devon' (I've seen this before).
'mostly' means to remove the last letter.
'support' becomes 'tee' (I've seen this before).
'devon' with its final letter taken away is 'devo'.
'devo'+'tee'='DEVOTEE'
'giving' acts as a link.
(Other definitions for devotee that I've seen before include "An enthusiastic admirer and supporter" , "One strongly interested in something" , "dedicated person" , "Zealous follower" , "Keen admirer" .)