Cancels concerning tolls (7)
I believe the answer is:
repeals
'cancels' is the definition.
(repealing is a kind of cancelling)
'concerning tolls' is the wordplay.
'concerning' becomes 're' (both can mean on a particular topic).
'tolls' becomes 'peals' ('peal' can be a synonym of 'toll').
're'+'peals'='REPEALS'
(Other definitions for repeals that I've seen before include "Annuls an act" , "Sets aside" .)