Concerned but not impartial (10)
I believe the answer is:
interested
This clue is a double definition.
'concerned' is the first definition.
(I know that concerned can be written as interested)
'not impartial' is the second definition.
(I've seen this before)
'but' acts as a link.
(Other definitions for interested that I've seen before include "Concerned" , "Partisan" , "Not impartial" , "prejudiced" , "Showing curiosity" .)