Charge is about right on the house (4)
I believe the answer is:
free
'on the house' is the definition.
(thesaurus)
'charge is about right' is the wordplay.
'charge' becomes 'fee' (fee is a kind of charge**).
'is about' indicates putting letters inside.
'right' becomes 'r' (common abbreviation).
'fee' enclosing 'r' is 'FREE'.
(Other definitions for free that I've seen before include "Not employed" , "Under no obligation" , "Exempt" , "Without cost; liberate" , "Unfettered" .)