Get to agree on London footballer dismissed (6,3)
I believe the answer is:
hammer out
'get to agree' is the definition.
(as in hammering out an agreement or deal)
'on london footballer dismissed' is the wordplay.
'on' is a charade indicator (letters next to each other).
'london footballer' becomes 'hammer' (West Ham United are called the Hammers).
'dismissed' becomes 'out' (I've seen this before).
'hammer' next to 'out' is 'HAMMER OUT'.
(Other definitions for hammer out that I've seen before include "Negotiate firmly" , "Devise with great effort - using mallet etc?" .)