Charge directed at liberals (4)
I believe the answer is:
toll
'charge' is the definition.
(I know that impose is a is a more specific form of the action of toll)
'directed at liberals' is the wordplay.
'directed at' becomes 'to'.
'liberals' becomes 'll' (a political abbreviation for liberal written twice).
'to'+'ll'='TOLL'
(Other definitions for toll that I've seen before include "Price exacted" , "Ring - fee" , "Ring - duty" , "Charge to use, eg, bridge" , "Tax - loss - duty" .)