Clue: Knowledgeable solicitor, say, on a roll finally with a great score in golf (5,5)
Answer: LEGAL EAGLE
Explanation: Definition: Knowledgeable solicitor, say
 LEG(in cricket, the on side/that half of the field facing away from the batsman's feet when standing to receive the ball) **plus**(on) A + **last letter of**(… finally) "roll" **plus**(with) EAGLE(in golf, a score at a hole that is 2 strokes below par, considered a great/impressive achievement).
Defn: What you might call/say, a smart/knowledgeable solicitor.