Great, no parking! One will charge (4)
I believe the answer is:
suer
'one will charge' is the definition.
(someone charging or suing)
'great no parking' is the wordplay.
'great' becomes 'super' (both can mean excellent).
'no' indicates named letters should be taken away.
'parking' becomes 'p' (abbreviation on road signs).
'super' with 'p' taken away is 'SUER'.
(Other definitions for suer that I've seen before include "One in court, perhaps" , "One seeking redress" , "person in court" .)