A person of no special interest (10)
I believe the answer is:
generalist
'interest' is the definition.
Both the answer and definition are singular nouns.
Maybe you can see an association between them that I don't see?
'a person of no special' is the wordplay.
I cannot really see how this works, but
'a' is found in the answer.
'no' could be 'n' (common abbreviation) and 'n' is found in the answer.
'special' could be 's' (common abbreviation as in Special Air Service) and 's' is found in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for generalist that I've seen before include "Non-specialist" , "All-rounder" , "Versatile ten [SCHOOLTEACHER]" , "Person with broad interests" .)