Impartial Liberal following frightful rant about European Union (7)
I believe the answer is:
neutral
'impartial' is the definition.
(I've seen this before)
'liberal following frightful rant about european union' is the wordplay.
'liberal' becomes 'l' (abbreviation).
'following' means one lot of letters go next to another.
'frightful' indicates an anagram (a frightful spelling).
'about' indicates putting letters inside.
'european union' becomes 'eu'.
'rant' with letters rearranged gives 'ntra'.
'ntra' enclosing 'eu' is 'neutra'.
'l' after 'neutra' is 'NEUTRAL'.
(Other definitions for neutral that I've seen before include "Having no personal preference" , "Bland" , "Not partisan, unbiased" , "Not taking sides in a war" , "not getting involved?" .)