One of minor concern to the legal profession (4,2,5)
I believe the answer is:
ward of court
'one' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'of minor concern to the legal profession' is the wordplay.
I cannot quite see how this works, but
'of' could be 'o' and 'o' is found in the answer.
'minor' could be 'ward' (I've seen this in other clues) and 'ward' is located in the answer.
'concern' could be 'co' (short for company - concern can mean a business) and 'co' is found within the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
The remaining letters 'fur' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for ward of court that I've seen is " Legally protected child or needy person".)