Hardliner wants exit terms renegotiated (9)
I believe the answer is:
extremist
'hardliner' is the definition.
(someone with extreme views or policies)
'exit terms renegotiated' is the wordplay.
'renegotiated' is an anagram indicator.
'exit'+'terms'='exitterms'
'exitterms' with letters rearranged gives 'EXTREMIST'.
'wants' is the link.
(Other definitions for extremist that I've seen before include "One far from moderate" , "Ultra" , "outwardly fanatical" , "One with very radical views" , "immoderate person" .)