Excellent Frenchman in goal (3)
I believe the answer is:
aim
'goal' is the definition.
(aim is a kind of goal)
'excellent frenchman' is the wordplay.
'excellent' becomes 'ai' (resembles 'A1', old-fashioned term for excellent).
'frenchman' becomes 'M' (abbreviation for Monsieur - like 'Mr').
'ai'+'m'='AIM'
'in' is the link.
(Other definitions for aim that I've seen before include "Point (gun); intention" , "Goal, objective" , "Focus on target" , "Point towards a target, or have ambition" , "Set sights on, target or goal" .)