At liberty to make no charge (4)
I believe the answer is:
free
This clue is a double definition.
'at liberty' is the first definition.
(similar in meaning)
'no charge' is the second definition.
(synonyms)
'to make' is the link.
(Other definitions for free that I've seen before include "Not under restraint" , "unoccupied)" , "Reef (anag.)" , "without payment" , "with no toll demanded?" .)