He may be objecting to modern arts perhaps (12)
I believe the answer is:
demonstrator
'he may be objecting' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'to modern arts perhaps' is the wordplay.
'perhaps' indicates anagramming the letters.
'to'+'modern'+'arts'='tomodernarts'
'tomodernarts' anagrammed gives 'DEMONSTRATOR'.
Can you help me to learn more?
(Other definitions for demonstrator that I've seen before include "One who shows how things work" , "shower" , "Rally participant" , "showroom car" , "Teacher - salesperson - someone on a march" .)