Criticises a government charge in speech (7)
I believe the answer is:
attacks
'criticises' is the definition.
(attacking is a kind of criticising)
'a government charge in speech' is the wordplay.
'a government' becomes 'at' (I can't justify this - if you can you should believe this answer much more).
'charge' becomes 'tax' (tax is a kind of charge).
'in speech' indicates a 'sounds like' (homophone) clue.
'tax' sounds like 'tacks'.
'at'+'tacks'='ATTACKS'
(Other definitions for attacks that I've seen before include "Assails" , "Fiercely criticises" , "Assaults" , "Invades" , "Charges" .)