Lawyer changed game causing harm (6)
I believe the answer is:
damage
'harm' is the definition.
(I know that harm can be written as damage)
'lawyer changed game' is the wordplay.
'lawyer' becomes 'da' (abbreviation for District Attorney).
'changed' indicates an anagram.
'game' with letters rearranged gives 'mage'.
'da'+'mage'='DAMAGE'
'causing' acts as a link.
(Other definitions for damage that I've seen before include "Impair or cause injury to" , "Physical harm" , "Harm; reparation" , "To vandalise" , "Deface, harm" .)