Locates on behalf of and allows one to win the case (5,3)
I believe the answer is:
'allows one to win the case' is the definition.
I can't judge whether this definition defines the answer.
'locates on behalf of' is the wordplay.
'locates' becomes 'finds' (I've seen this in another clue).
'on behalf of' becomes 'for' (eg speaking on behalf of or for someone else).
'and' acts as a link.
Can you help me to learn more?