Expertise to claim island is in Lake Michigan initially (15)
I believe the answer is:
professionalism
'expertise' is the definition.
(professionalism is a kind of expertise)
'claim island is in lake michigan initially' is the wordplay.
I cannot really see how this works, but
'claim' could be 'profess' (professing is a kind of claiming) and 'profess' is present in the answer.
'island' could be 'iona' (Scottish island) and 'iona' is located in the answer.
'is' is found in the answer.
'lake' could be 'l' (geographical abbreviation) and 'l' is present in the answer.
A single letter 'm' remains which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
'to' is the link.
Can you help me to learn more?
(Other definitions for professionalism that I've seen before include "Competence of experts" , "Skill not displayed by amateur" , "Doctor needs to show this skill" .)